Chmod Question

[محروم.كوم]

Hey,

I just wanted to ask wich files i have to chmod, becuse it confuses me for some people say chmod on folders is that example 777 and php files are example 555

So i really want to know wich files do i need to chmod when i upload them to my ftp ?
And wich chmod should they be, i have always hosted localy so never been in need to chmod before :P

Thanks __DEFINE_LIKE_SHARE__