Please, after installing Scratch, open the application and give a try to the menus, buttons and generally everything the software offers you! You need to get acquainted with Scratch.
For example you can try to change backgrounds, add sprites, delete sprites, apply instructions to sprites (scripts) and anything you can think of.
I know that you probably will not be able to do much. It is Ok. It is important to try.
After this effort you will have even more questions. Maybe some of the questions you had earlier were solved. Be certain that in a few weeks all your questions will get answered.
I know you’re in a hurry to create games. But it is not a simple process! It needs to be done carefully and step by step.
I promise you that you will finally do it!
After 20 minutes take a break!
Continue tomorrow or another day, by doing exactly the same!
Did you do it?