OS 10.5 - unable to file share

Hello!

OK, I'm pretty sure all of my sharing options are properly set...
system preferences -> sharing, and then I have "File Sharing" checked.

My father and I both have macs... i have a macbook alu, and my father has an iMac (alu). We can see each other on our network, and he can share files that I can see and keep, but I can't share ones of my own.

I've tried both ways - I've tried putting folders into my public folder, to no avail.
I've also tried right-clicking the folder and then choosing "get info," then dropping down the General tab, and then checking "Shared Folder"... and nothing.

Hewp!