I'm lucky, not only did my Nana teach me to cook, she taught me to enjoy cooking...
As far as yams, my mother in law just rubs oil on the skins, pokes them in several spots with a knife and microwaves them for about 25 minutes (usually about 3 at once). As far as my favorite style of cooking them, I have a great recipe where you peel them and cut them up (or have your brother/husband/adult son/other big strong male do it, since they're a real pain to cut when they're raw!), cook them with water, sugar (I know, bad girl... :devil: ), cinnamon and allspice and add a teeny bit of butter. Absolute yum.
As far as the Yam/Sweet potato debate, I've had both Southern-style sweet potato pie and Filipino-style yam flour cake, and they're both yumalicious...
If you want to start on a bit of cooking for yourself, start simple, and with recipes that you can "customize" at will - change spices/seasonings, substitute one meat/fruit/nut for another, etc. The more creative you get to be with it, the more you'll enjoy it, and the easier other dishes and styles of cooking will come to you.
--Robin