You don't need to activate the Apache web server. amuleweb is a web server in and of itself, although not nearly as full-featured as Apache.
You need to run aMule, go to Preferences -> Remote Controls. Enable running amuleweb at aMule startup. Enter a password for Full Rights access. This is the password that a web visitor would have to enter to login to amuleweb.
Also enable Accept external connections. amuleweb connects to aMule via what we call an "external connection". Enter a password there, too. This is the password that amuleweb uses to authenticate itself to aMule.
Restart aMule. You should now be able to connect to amuleweb by directing your web browser to
http://localhost:4711.