If you are stitching an item that will not be washed you do not have to use real knots. Thread your needle with both ends of the thread so that you have a loop at one end.When you insert the needle for your first stitch, do not pull the thread all the way through. Do your first stitch and now that your needle is to the underside of the fabric, put the needle through the loop and you will have a knot of sorts.
When complete, run your needle and thread through the last few stitches. (it's okay if the stitches are not very even, they will get better with practice.)
You will have to end this stitch with a real knot. So when you make your last stitch, instead of just putting your needle through it, put your needle through it 2 or even 3 times and then pull. This will give you a real knot.
How to sew on a button:
This is what it will look like when you pull.