How to create new Unity project
To create new Unity project you have to:
1. Open Unity Hub
2. Select "Projects" Tab (if it is not already selected by default)
3. Click on blue "New project" button (in top right corner of Unity Hub)
4. Pick project template
(depends on what kind of the project you want to make 2d, 3d,...)
5. Name your project and pick location on your hard disk for it
6. Click on blue "Create project" button (in bottom right corner)
Of course, I assume you already have Unity Hub and some version of Unity already installed on your computer.