The two editors and which one to use
Microsoft ships two editors that can build the same projects. Choosing between them is easier than the marketing suggests.
The free editor
The free editor installs quickly, opens web projects, runs them in a browser and includes a debugger. For every lesson on this site it is sufficient. If you are learning, start here.
The paid editor
The paid edition is the same workspace with extra tooling for large teams, testing and database work. It does not teach you anything the free edition cannot. Buy it when a job requires it, not before.
They share one project format
A project created in one editor opens in the other. That means you can start free and move later without losing work.
Decision rule. Use the free editor until something you are paid to do genuinely needs a paid feature. Then switch. The setup track covers installation for either one.
Whichever you pick, the next stop is the solution explorer, which is where every file in your project is listed.