If it's an odd-shaped present, then it's harder to wrap. If it's a box, then you have it easy. If not, you can go to the dollar store and buy a gift box to put it in. If you still want to wrap that gift box, or if the present already comes in a box, here's what you do:
First, lay the box on the sheet of wrapping paper. Cut enough paper to fully go around the box, and leave about an inch over the fold. Then, make sure to have enough to cover the sides, but cut off any excess. The key is not to have too much excess paper on the sides, or it will look poofy.
Then, put a small piece of tape to hold the paper around the box. Then work on the sides. Fold the top flap down, and then crease the paper on the bottom at an angle, so that it stays firm at that fold. Then fold up the bottom flap of paper, fold the edge over so that it looks neater, and then secure with a piece of scotch tape. Then repeat on the other side of the package.
Just remember to make neat folds, and lay the fold flat with your fingernail. it'll help keep the paper steady.