Samsung T639 Games

I have some Games for my cell. when I copy them in to the Folder called other files. I then go to fun & spps on the phone. go to other files and install games.
it tells me the unsupported file type.
I did a google search I think I learned the phone is locked so you have to download off the web to get games to install.
I found unlock codes for many phones but not mine.
is there a way to get around this with out paying the cell phone company
the download charge?