There are lots of ways to hold your hook: usually the predominant hand holds the hook while the other hand holds the slip knot
There is no right or wrong way, whatever feels comfortable for you.
The yarn needs to be threaded through the fingers. Again, you need to see what feels right for you, here are some suggestions:
The yarn needs to be held with tension so that the stitches are a regular size, this comes with practice but it is a good habit to raise either your index or middle finger and hold the work with the other so that you can easily progress to more advanced stitches.
Now you’re ready to learn how to make a slip knot