As Ianrauk has mentioned, Youtube is your friend when it comes to tutorial videos.
In short, remove the original handlebar tape and pull back the rubber covers. You should find you can just pull them over the front of the shifters (no need to take them off, just enough so you can wrap some tape over them).
In your pack of tape, you should find two small strips of tape, two rolls of tape, two end caps and if you're lucky some tape to secure it afterwards.
Take the two small pieces of tape and fold them under each of the shifters.
When it comes to the rolls, some prefer to start at the bottom, others the top. Personally I go from the bottom end of the bars, slowly and carefully ravel it around up until you come to the shifters, here you shall want to go over the top (the bottom has the smaller pieces of tape on, no need to do it fully as some of it shall be covered by the rubbers). Continue wrapping as normally and either use the entire roll or cut it if it's too long. Secure it with the tape and fold the rubber back over.
Important things to remember, make sure you keep it tight, and try and keep the spacing even between turns. Don't be afraid to start again if you find you haven't got enough tape, just unravel it and make your spacing a bit further apart.
Good luck!
(And it might take a couple of times to get it perfect, it'll come naturally after that)