How to get back to the command prompt after using a command in linux terminal program

Today I practiced using linux terminal commands. I noticed that after typing some commands, I was not brought back to the command prompts or the ~$ sign prompt. On my terminal, it looks like this
myname@myname-desktop. I am using an ubuntu system on a virtual pc for windows.

I tried using the following command -- tail -f. It showed text I wrote on another file. When I was done using this command, I could not get the $sign prompt to return to my screen. HOw do i get back to this prompt after using a command like this without having to shut down the terminal program, which is what I've been doing, and restart it again.

Thank You.