I typed a command and the terminal opened up a new screen for me, but I can’t seem to type anything or go back to my command prompt! Help?

Looks like you've taken a little trip to Vim land! :)

Vim is text editor that is often the default used by your terminal. For example, if you've typed 'git commit' but forgot to include your commit message, the terminal will launch Vim for you so that you can enter it. In order to add any text, you'll first need to type 'i' (for <insert>). Once done, you'll want to hit escape ('esc') followed by ':wq' - which will save and quit the editor.

You should now be back to your regular command prompt.