Once your system boots, you'll be presented with the login prompt. Log in using the personal login and password you selected during the installation process. Your system is now ready for use.

If you are a new user, you may want to explore the documentation which is already installed on your system as you start to use it. There are currently several documentation systems, work is proceeding on integrating the different types of documentation. Here are a few starting points.

Documentation accompanying programs you have installed can be found in /usr/share/doc/, under a subdirectory named after the program (or, more precise, the Ubuntu package that contains the program). However, more extensive documentation is often packaged separately in special documentation packages that are mostly not installed by default. For example, documentation about the package management tool apt can be found in the packages apt-doc or apt-howto.

In addition, there are some special folders within the /usr/share/doc/ hierarchy. Linux HOWTOs are installed in .gz (compressed) format, in /usr/share/doc/HOWTO/en-txt/. After installing dhelp, you will find a browsable index of documentation in /usr/share/doc/HTML/index.html.

One easy way to view these documents using a text based browser is to enter the following commands:

$ cd /usr/share/doc/
$ w3m .

The dot after the w3m command tells it to show the contents of the current directory.

If you have a graphical desktop environment installed, you can also use its web browser. Start the web browser from the application menu and enter /usr/share/doc/ in the address bar.

You can also type info command or man command to see documentation on most commands available at the command prompt. Typing help will display help on shell commands. And typing a command followed by --help will usually display a short summary of the command's usage. If a command's results scroll past the top of the screen, type | more after the command to cause the results to pause before scrolling past the top of the screen. To see a list of all commands available which begin with a certain letter, type the letter and then two tabs.

Even the usual login screen shows lot's of useful information regarding documentation, support, basic system information and last login data:

Welcome to Ubuntu 18.04 LTS (GNU/Linux 4.15.0-22-generic s390x)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Tue Jun  5 17:17:17 EDT 2018

  System load:    0.01              Processes:              180
  Usage of /home: 0.2% of 20.18GB   Users logged in:        1
  Memory usage:   4%                IP address for encc000: 169.254.232.169
  Swap usage:     0%                IP address for virbr0:  192.168.122.1


0 packages can be updated.
0 updates are security updates.

Last login: Tue Jun  5 17:46:34 2018 from 10.177.178.179