I'm pretty fond of cockrings, which may not come as a big surprise, but as I heard that some guys have difficulties in getting these on and especially off again, I made up my mind, to give you this "how-to".
For starters, a little theory, about how the penis is designed, and how it works:

What you see here, is a drawing of how the penis is designed 'on the inside'.
The 3 pink areas represent the 3 spongy erectile tissue chambers in the penis,
as it would look, if you saw it 'cut through' across the shaft. These erectile
tissue chambers fill with blood, when you get a erection
Normally the pc-muscle closes off the 'return flow' from the penis, thus
creating the 'hard on'.
You can achieve the same effect with a cockring, and unlike the natural way, the
cockring does not release the pressure, letting you get a bigger erection and/or
keep the erection for prolonged periods of time.
The trick, when you want to remove a tight cockring, is to press on the
cockring, to let blood out of one of the erectile tissue chambers, one at a
time.
Cockring on...
1/ At first, you grab your penis,
and pull as much of the skin as you can, out over the penishead. (This is best
done with a flaccid penis... *S*).
2/ Then you pull the skin through
the cockring, and pull the cockring as far 'down' the penishead, as you can.
3/ Next you tighten up your
pc-muscle, (pubo coccygæus) thus pressing the penis forward, inside the
skin, which will force the penishead through the ring. (And if it does not,
the ring is too tight - DO NOT proceed, but get a larger ring).
4/ Now you pull the ring as far
'down the shaft' as you can, and as you can see here, the effect is immediate.
5/ Now the cockring is in place,
and as you can see, it's giving a nice hard eretion. In case you want more, just
'pump' your pc-muscle.
Cockring off...
6/ When you want to get the
cockring off again, push the cockring 'upwards and to the left hand side' in
order to let blood flow out of one of the 3 spongy erectile tissue chambers.
7/ Next, you push the cockring
'downwards', in order to let blood flow from the next of the 3 spongy erectile
tissue chambers.
8/ Finally you push the ring
'upwards and to the right hand side', in order to let the blood flow out of the
third, of the 3 spongy erectile tissue chambers.
You may need to repeat steps 6 to 8 a few times, while you constantly pull the cockring towards your penishead, but the effects should be clearly visible.
9/ When you have the cockring
placed just 'behind' the penishead, you push the cockring downwards, as the
penishead is a prolongation of the lower spongy erectile tissue chamber.
10/ Squeeze the skin, in front of
your penishead, to force your penishead through the cockring.
11/ Having gotten the cockring out
over the penishead, it's simply just pulling it out over the skin, 'caught' in
front of the penishead.
NOTE: If this gives you pain, you've chosen a cockring, which is too tight
for you. The ring I'm using, in the pictures are 30 mm 1 3/16"
across (on the inside), and is just about as tight, as I can handle it. What
size fits you, is impossible to say, but if you measure your erect penis
'across', and reduce the measure by 5-10%, you should have a reasonably safe
size to start with.
It's always better, to start out with a ring a little too large, and find that
it could have been smaller, than getting stuck, with a ring on your cock, that
you can't get off.
(I've checked with the local emergency medical facility, and they say, that in
this situation, they would either apply a hacksaw or a pair of bolt scissors, in
order to cut the ring in two places, in order to remove it. (I'll leave that
picture, to your imagination, for a moment!).
Of course there are more possibilities with cockrings, than just putting one ring around your shaft.
One of the possibilities, are to sew i.e. 3 of them together, to form a triple-cockring, which you can see more about, if you click here, or if you click the picture underneath this text.
Little by little I'm getting myself a collection of steel-rings (which is far from complete by now), and this is opening new possibilities, i.e. to make combinations, or to use more rings, at one time. Here I'll show you two other possibilities, and then I'll let your own imagination tell you what might be possible with....*LOL*
Twin-rings:
If you're careful, when purchasing your rings, it is possible to combine
them, in order to i.e. have them working 'side by side'.
Notice that the rings used here can not slide over' one another, which is
an important point, at the larger ring is 'caught' by the smaller one next to
it.
Maybe I should have been more careful, making certain, that the two
double-rings, grabbing my balls in the above pictures, were 'evenly
distributed', but there is a tendency, that the first ball to 'go
through' the double ring, will grab a little more ballsack-skin, than the second
one will be allowed to get.
If it's important to you, to get an even distribution of the available ballsack-skin,
I suggest that you use a mirror, in order to aqdjust for this, after
having gotten the second dual-ring ring mounted on your ballsack.
More rings:
It is certainly possible to wear more than one ring, in either 'position' at one time, as you'll see below here. All you need to do, is to pull one after the other i.e. over your cock, or you ballsack. I'm still dreaming of what it will feel like, when I get cockrings enough, to actually cover my complete shaft, to just behind my cockhead, but you'll need to pay attention, when putting them on, as you get a rather un-pleasant experience, if you get a little skin 'peeking out' between the rings, as this will squeeze the skin captured, when your cock (or ballsack) is swelling, causing the rings to 'bite' onto the skin - so take care there, unless you like the pain, of course...
I'm still dreaming of the day, when I get rings enough, to cover my whole 'shaft' to just behind my cockhead...*S*