Hi, I would say programs like ICQ or mIRC (don't know AIM) are an easy way to trade files with friends (it's easy to use and more important: it's easy to find your friends).

Any other method may be more complicate, you at least need to know the IP/port of your friend (or tell them your own). The port is usualy 6346, but the IP is more difficult to find - can change if you are using dynamic IP and willl be more difficult if you are using are firewall/proxy. So I would say... this is definitely something for more advanced users. Sorry, anyone can give a better solution?
Actually if you are interested: It is possible to trade with friends (even with dynamic IP or firewalls), just ask a friend for help. A very good idea is an FTP-server and a permanent host adress (eg.g www.no-ip.com), advantages: the FTP-protocoll is the fastest and music/cookrecipes sharing between close friends is good if you have rare taste (some say bad taste).

Anyway, when using Xolox or Morpheus or other P2P programs, you will find nearly alll you need (depending on what you are looking for).