Making A Slipknot
Start by leaving a tail, and make a ring out of your yarn. you want to leave a tail length that coordinates with the amount of stitches you need to cast on.
Next, you will take the ring that you made out of yarn in the last step and pull it over the other strand of yarn that is on the top of the crossing section from where you made the ring.
Now, you will take the strand of yarn that is in the middle of your ring from the last step.
Now you will grab the strand of yarn that was in the middle of your ring and grab the two strands of yarn that were at the bottom of the ring.
You will now pull on all of those strands at the same time, this will cause a slipknot to form.
Casting On
Place your slipknot on your knitting needle with the tail of your slipknot facing away from you.
Place your fingers between the two strands of yarn from the front. Wrap the rest of your fingers around the yarn strands below your fingers, and push out with your two fingers that you placed between the two strands of yarn to tighten you slipknot to the knitting needle. (don't make this too tight or you will not be able to knit it)
Place your thumb and your pointer finger between the two strands of yarn again.