AFAIK, if you're cooking from scratch, low-sodium cooking is just about not adding extra salt, and checking any processed ingredients you do use (e.g. stock cubes, canned vegetables, etc.) for added levels.

Some possibly-useful links on things to watch for:

http://www.abbottnorthwestern.com/ac/hearthealth.nsf/page/sodium
http://diabetes.webmd.com/diabetes-understanding-salt

If you're very new to cooking, I'd suggest mastering some very-quick-and-easy recipes that you can make (with infinite variations) when you'd normally eat a convenience meal -- e.g.:

basic omelette or scrambled eggs with vegetables
simple cooked fish and salad
stir-fry (almost anything can go in a stir-fry!)
pasta with various simple sauces

All of these can work fine without any salt at all (e.g. my not-technically-poached salmon).