Canon SLR Cameras

can i use my canon 35mm lens on the 40D?

i have found some on ebay but are they to be trusted ? they look kinda cheap please help me ?

I am fairly new to cameras and photography. I have been doing research about this camera for a little while and I have come to a conclusion that most people recommend to buy just the body and the lens seperately. How do I know which kind to buy? Is there a website that can help me make a decision?
My dad gave me his old Canon camera from the 80’s which came with new lens. Umm Im not too sure if this is what they are called but one of them says Canon Lens FD 50MM 1: 1.4 (Made in Japan) and the other says Canon Zoom Lens FD 35-105mm 1: 3.5 (Made in Japan)