The other three are source and you didn't need to download those - that's only if you want to rebuild the system or parts of it, or otherwise examine the source, including the build scripts.
You need to create a user account for general work and 'adduser' is a handy wrapper for that. Run that as root and answer its questions.
You should have established a default window manager in setup but, if not or if you wish to change it, running 'xwmconfig' is a way to change that.
Try reading
the SlackBook for more information.
-- Oh, and welcome to LQ/Slack.