(newbie) A problem with Apache 1.3.x

I installed Apache on my Mandriva 2007, but when I try to put the server
up, it sends me an error like this:

[root@localhost bartek]# httpd
(98)Address already in use: make_sock: could not bind to address [::]:80
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
[root@localhost bartek]#

I think I've got the port used by something else, but I don't know WHAT
and HOW to close it. Is it possible that I've got a bug in my httpd.conf?
I know it's possible, but is it connected with that? I wish somebody could
tell me how to do it step by step... I'm a complete newbie when it comes
to Apache...

Thank you in advance,
BM