Go to %APPDATA%\MaxCoin\maxcoin.conf
Update this file so that it matches this https://github.com/Max-Coin/clients/blob/master/example-maxcoin.conf file, with the username and password set to whatever you want.

Open the terminal (Windows key + R, type cmd) and traverse to the directory that the .exe file is stored in (type cd *directoryname*)

Type maxcoind.exe --daemon

And the miner will begin mining, keep an eye on the %APPDATA%\MaxCoin\debug.log. This will let you know the status of miner.