Don't worry it's pretty easy, much easier than covering a cake in fondant in my opinion
Just roll out the fondant and find a circle cutter that is a similar size to the cupcake and cut out the fondant. Then just put some buttercream like seaqueen said to stick the fondant to the cupcake, or in my case my cupcakes are pretty moist so I just put it on stright away (or you can use sugar syrup to make it stick). Then just gently rub the sides to make the fondant shape around the cupcake...
Hope that helps