First check if apache is running on your Mandrake box. -->
# netstat -a
check if apache runs and behind the default port 80.
If apache runs on a different port type http://localhost:PORTNUMBER/
If apache doesn't run fix this first. --> (if apache is installed)
# apachectl start
If apache runs, and your browser gives a problem. Check if there is a firewall running, and allow conections on port 80.