File Formatting/Loading

Ok this is something i dont know very much about at all because i have never been able to find any information on it. I understand how people would use binary type images for there resources in games, but this would of course require making an editor to output one. I understand how ASCII text files would work, but if this is how, what are some of the ways people go about doing this? Any tips, links or info on any subject related a loading engine would help greatly, thanks.

Google SDL.

i am talking about making my own system

http://www.wotsit.org

Thanks ;)