first off not to descurage you or anything, but collison detection and response is quite math intensive, but luckily there are some good resourses and frameworks that can help out with this. if you are just looking for a quick fix a toolkit or library is your best bet, otherwise if you want to write it from scratch it is quite complex, but there are some good resources out there.
the Colision detection toolkit is a good one: http://code.google.com/p/collisiondetectionkit/
anther good framework is box2D, but it is a bit more involved, because it requires everything to be set up in a very specific way, but the advantage is, there is a lot of good documentation and less math involved. :
"http://box2dflash.sourceforge.net/" (I can only post two links because I'm somewhat new to the site, so I had to quote the URL... sorry)
if you would like to learn about the way collision detection works here is a pretty good tutorial on the subject: http://www.metanetsoftware.com/technique/tutorialA.html
the basic idea in making a ramp like this work in a game, is you need to figure out if your two objects are intersecting... if so you need to determine the amount they are intersecting and find a the vector orthogonal(aka perpendicular) to the surface of the ramp, to push your player or object out of, so it does not intersect... this process is checked every frame or so to make sure the object does not go inside the other object.