Let's see how to start the installer:
wwwroot(location where you have installed Mahara) in your Internet browser. For example, visit http://mysite.tdm.info.
If you don't see the GNU information screen, it is likely that you have done something wrong. Mahara will typically give you a message at this point explaining what the problem is. You can then have a look over at mahara.org for some help with fixing your problem.