It is not too hard but acquiring the "touch" takes time. Get a good "how to" book from Home Depot on electrical stuff.
If you leave the ceiling box and use a swag the pendant light it will be easiest. Just get a cover for the ceiling box (usually white) and a little decorative wire+chain. Use a well anchored ceiling hook and you can hang the pendant without messing with the drywall. Simple to do and your wife will owe you BIG TIME.
If you want to move the box, it gets harder. Things get in the way (ceiling joists) and the existing wiring might not have enough slack to get to the new box. I like "old work" ceiling boxes because you can install them securely -- but you want the fit to be tight, so cutting the drywall should be done carefully. If you can get the wiring to the new box, the pendant light can be relocated. The old box will have to be drywalled . . . if you do not know how, there is a whole new world of repair awaiting you.
Your best bet is to ask friends and friends-of-friends for help. Someone can walk you though all the steps and keep you from messing up the kitchen. My son-in-law is in that category . . . but he has me to re-frame and re-wire his entire kitchen. Oh, and show him how to do bullnosed drywall edges.
Good luck on this new chapter in your life!