Once you learn the basics, you can learn a fun trick to do with condoms. Here's how to put a condom on your partner using only your mouth:
~ Open the condom package and make sure that the condom is going to roll down.
~Place the condom in your mouth, gently holding the edges with your lips.
~Make your mouth into an O shape, still holding the edges with your lips.
~Without letting your teeth touch the condom, use your lips to push the condom over the head of the penis and roll it all the way down the shaft, still using only your lips.
~Run your lips up and down the shaft to squeeze the air out of the condom.
~Be very careful not to let your teeth come in contact with the condom.
~Check with your hands to make sure it is on properly.
As you can see, condoms are quite simple to use an can even be fun to use once you get accustomed to them. And you should use them because, besides being a method of birth control, they are the only way to stay protected against sexually transmitted diseases and the HIV virus.
Source - The Complete Idiot's Guide to Amazing Sex