Pretty good job for your 1st time.
It looks pretty easy for you at that weight.
At a heavier weight the technique you are using will not work too well.

The head of the dumbell needs to be more behind your head and the bell should be oriented with the ends more left/right as opposed to front/back as you have it.

You’ll also need to be much more explosive as you press.

Overall, good work for the 1st day as I said.