Issues putting on condom
I am recently circumcised, and was trying to put on a condom for the first time with my new unit...er... anyway, while it looks so easy when reading up instructions (or seeing a video of someone putting on on a cucumber or whatever), I'm finding that while trying to unroll it over the shaft, it kinda... unrolls in place, if that makes sense. So like, it unrolls, but the ring never makes it over the glans, leading to a partially-unrolled condom that isn't on me (and therefore doesn't seem to be salvageable).
1) Am I doing something wrong? What is it?
2) How do I know what the right size is, based on the ring size wrt the glans?
3) I was hoping to experiment with various sizes, but the packs didn't seem to have sizes (medium, large, etc.) on them, so I figured they were one size fits all, but I keep reading about this magnum business. Is there a secret coded 'size' on the box that I can't see or something?