mail function

hi all, I cant seem to get my mail function to work. OK so i am a noob, that might have something to do with it. I am using a script I found called the HTML Mime Mail Class, which does everything i need except actually send the mail. I am guessing that there is some config problems, but i am not sure. Even when i try and use the mail() function i get a server error. So i guess that my problem is that my return address is messed up. Does it have to be my own domain, or the domain that the server is running on? Can i set the return address as a hotmail account, or do i need my own server mail program? And is there anything that i need to config in the php.ini file? Thanks for helping, T P K Cannell