MAMP PRO is saying that port I want to use for Apache, MySQL is being used

MAMP PRO may not be able to run on the web server, database or other port you want to start a service on. You may see an error message indicating that the port is in use. MAMP PRO will automatically suggest a different port.

http://documentation.mamp.info/en/MAMP-PRO-Windows/Settings/Ports/

To confirm that there is another process running on a port (port 80) you want to use, type the following into the terminal.

netstat -na | find "80"