Thanks so much for all the advice! I've bookmarked the sites you gave me and had a look too.
I know what kind of yarn I like so far.... plain, worsted for socks (tho' I'm thinking of branching out to some dk yarn) and softy bulky for sweaters.
I think my problem is... I'm not visualizing what the weights are but I'm thinking that will come the more I go to my LYS and the more I do research online.
I sincerely appreciate you all for answering me on this question.