You configure the bash prompt by the PS1 variable. You can set the prompt to hello with PS1=hello. This is explained in the bash man page under the PROMPT_COMMAND section.
You can make the prompt more elaborate by using escape characters and variables in PS1, for example:
will change the prompt to the name of your home directory. Use the command:
to see other variables that you could possibly use. Other things that you can include in your prompt are described in the bash man page under PROMPTING. For example:
Once you get PS1 the way that you want it you can make it permanent by placing it in a bash profile file under /home/user/. Different distributions use different bash profile files. Look for .bashrc, .bash_profile, or .profile.