Before you start tying your shoes, make sure that there are no knots in your laces. Get your laces straightened out and cross them over each other across your foot. Then, you can put one of the laces under the other and loop it around. Afterwards, tighten your laces down on the top of your foot. Next, make a loop with one of your laces. Wrap the other lace around the loop and put the loop underneath. Lastly, you need to pull the other lace through the loop until you have two loops. Tighten the laces down on the top of your foot so they won't come undone.
You will probably not get this perfectly right the first time. You'll need to practice- probably at least ten times- but you should soon be able to tie your shoes without any problems.