Begin with the useful slip knot

Open the loop to Make a Stitch

Once you’ve made your slip knot, put the needle with the slip knot in your left hand and the empty needle in your right hand.

To begin the cast on:

Slide the right-hand needle into the loop on the left-hand needle, from front to back. This is known as “opening the loop” because you’re piercing the loop and leaving it open for working a stich.

Wrapping the Yarn

The next step is exactly like the next step in forming a knit stitch.

You will loop the yarn that is attached to the ball over the point of the right-hand needle, going counter-clockwise.

Be careful not to loop the yarn over both needles.

Hold the yarn loosely in your right hand.

Watch Your Tension

Don't pull too tightly as you wrap or your stitches will be hard to work on the next row. Your loops should be tight enough to stay on the needle, but loose enough to slide the second needle through with ease.

This is a concept known as tension, and like in other parts of life, too much tension makes things more difficult. As you become a more experienced knitter, you'll learn what feels like the right amount of tension in your work.

Pulling the loop through

Here's the only tricky part in mastering the knit cast on and knitting in general. It is a simple movement of the needles that creates a new loop and it seems a bit awkward at first. With practice, it will become second nature and you will not even have to think about it.

The goal in this step is to keep the loop you just made on the right-hand needle while bringing it to the front of the work. The slip knot stays on the left-hand needle.

Keep holding onto the yarn with your right hand so it doesn't get away from you. Slowly slide the right-hand needle down so the loop gets close to the tip of the

needle, but does not slide off. At the same time, the right-hand needle comes out from behind the left-hand

needle.  When the right-hand needle barely comes out from behind the left-hand needle,

give the right needle a little push with your left index finger to push the needle in front of the left needle.

Finishing the Stitch

You're almost done casting on a stitch with the knit cast on.

Now all you have to do is slide the loop that's on the right-hand needle onto the left-hand needle, above the slip knot loop.

You now have two stitches. This isn't the way you finish a knit stitch, but all the other steps are the same, so once you get your cast on finished, you'll be ready to roll with the knit stich.

To cast on the desired number of stitches, simply keep repeating these steps until you have the required number of stitches on your needle.

These directions were from The Spruce

https://www.thespruce.com/knit-cast-on-2116503