Okie ... I'll try to break it up a bit
From A Simple Condom Primer
5) After he has an orgasm and ejaculates (or doesn't but you're finished having sex), hold the base of the condom (the rolled-up part) with your hand and hold it with your other hand by the tip. Pulling it off by the tip alone not only makes a big mess, you could drip all over yourself what you just worked so hard to keep out.
It's easier to take the condom off when the penis is soft ... That is usually after he has orgasmed or ejaculated (one is not always the other, and they're not always together). The rolled up part is where the his penis is attatched to his body (that sounds funny, but i don't know how else to say it lol) ... You want to grab that w/ your index finger and thumb, so you'll be ready to hold it closed and prevent spilling it's contents, should the condom tip. Using your index finger and thumb you'll want to gently tug on the condom at the end of his penis ... Where all that sperm is hanging out waiting to be disposed of.
"He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever."