Hey /fit/

I'm trying to work on my stomach/core strength to help out with climbing (and a better looking stomach is certainly nothing to complain about). I'm pretty new to it, so I think it's probably safe to say that at the moment I have none.

So anyway, I'm starting out with just trying to do a few simple excercises daily, the main one being ab crunches. However, I'm unsure about of lot of things about them. How high should I be trying to lift my upper back off the ground (lower back should remain on the ground right?) I'm not even sure if I'm lifting myself high enough for it to count. Also, I'm worried that I'm straining my neck a lot while doing this. Would I be better off starting with just sit-ups or something? How much difference is there between ab crunches and sit-ups (besides the motion).

Sorry for all the questions, and thanks in advance for any responses.

Pic related I guess...kinda