Now that you can log in and move easily between directories and see which files are in your directories, you'll want to be able to edit those files. To do this, you'll need a program that allows you to edit the characters in a file. If you have worked in Microsoft Windows, you probably have used a program such as Microsoft Notepad, WordPad, or Word to do this. As you might imagine, these are not available in Linux.
There are several choices, all of which are free. I am going to show you how to use an editor program called Emacs. Other possibilities are programs such nano, vi, Vim, and gedit. There is nothing more religious than conversation among programmers about which editor to use, so if you have a strong opinion, you are probably already used to using one of these editors. The vi and nano editors are included...
