A friend of mine gave to me an used canvas of some jewelry or perfume advertise. Although I had better wished she introduced me to the model, I thanked her and decided to make a fast wood frame and hang it on the wall. It's a very simple instructable, but anyway it could give you some cue to reuse a nice advertising poster.
You need to take measures of the canvas, and assume a thickness for the wood profiles. If you don't find the right thickness, remember that the more thick is the profile, the shorter its length should be. This is because you have to turn down behind the frame the edges of the canvas.
If you buy the wood frames in a shop with cutting service, you could make the cut the right length, and avoid some work with hacksaw and angular guide.
Then you need a staple gun. Mine is very cheap because I rarely use it, but it's very handy if not essential for some projects.