Most Tarot decks they sell come with a little white book, or a guide that teaches you what each card means. Reading that book alone will help you greatly because each deck some times have different meanings (ect. different pictures, types, order, and sometimes leaves out the Minor Arcana). I really do not trust other websites (unless I am searching for spreads) on how to learn because their meaning of the cards could be how their deck runs things while your deck is totally different.
Just read the guide a bit and do a few readings on yourself should do the trick on getting you started. Remember you do not have to rush things, take it slow and steady to learn as much as you can.
Karma isn't really in the cards because it really doesn't make sense. If the cards are telling me of bad news and I break it to them I won't get bad karma because I have not caused the bad news. Same goes with good news and neutral news.
Last note, once you get a few weeks into tarot and you still desire to keep on learning than you can message me and I'll give you a list of good tips and books.