There are many different ways to cast on when beginning a project. An old faithful cast on is the long tail cast on. This is a good video showing how to do it.
Another good cast on, though I rarely use it, is the knitted cast on. You are actually knitting the stitches on to your needle. In this video, she mentions the thumb method. Do not use the thumb method. It is the way many of us remember learning, but it is not a good cast on, does not leave a nice edge and Elizabeth Zimmerman, the queen mother of knitting, says not to. Enough said.
My favorite cast on for socks or mittens, is the Twisted German cast on. I confess to learning this on You Tube one night when my husband was traveling. I stayed up until 3:00am and watched it a million times until I got it.
Once you have casted on, you can knit your first row. Start small, 10 stitches. At the end of each row, count to make sure you are not adding or missing stitches. Do not start with fuzzy, fancy yarns. A nice wool from a craft store is perfect to learn on.
And skip the metal straight needles. Bamboo needles are lighter, your stitches won't slide off and you won't get so frustrated. I want you to like it!
This is for you, Cate!