Procedure to Make a ChainEdit
1. Make a slip knot with your yarn. The resulting loop is where your crochet hook goes. Put the hook into the loop and pull the knot so it is able to slide easily along your hook but no looser.
2. Yarn over your hook. (This means essentially wrapping your yarn once around the hook so that it can hook it, but it is more usual to move the hook to wrap it in the yarn. See linked page for more instructions.)
3. Draw up a loop. This means hook the yarn you just wrapped on the hook and draw it through the loop already on the hook.
--- If you have trouble drawing the chain through your loop, this means you are holding the yarn too tightly. Achieving proper tension is one of the most difficult crochet nuances and will come with practice.
You have just made one chain (1 ch in crochet abbreviations).
There are alternatives to the chain to use for a foundation for other crochet stitches. These include foundation single crochet, punching holes in a fabric, and using already knitted or crocheted material, among others.