First you need to choose a spread to door even just a daily drawing would work. Once you choose the card(s) you look up the meaning. Most tarot card packs come with a little booklet that tells you what each card means, then you just simplily have to interpret the meaning.
First, you should study them, learn their meanings, how they work, etc. If you are looking for a specific book to read, you may want to read "Tarot for Beginners" -Lisa Chamberlain. She is an amazing book writer, I highly recommend her. If you look in the video section on here, you will find some videos about tarot cards and how to use them.