Fresh install of OS X with AppStore version
Burn Mountain Lion to a disk or USB. 

Restart computer, hold down the option key when you hear the ring tone sound. 

Select the disk/USB, after it loads open Applications->Disk Utilities from the top. 

Select your HDD.

Go to partition and select 1 from the drop Volume Scheme, or however many you'd like. 

Select Mac OS Extended (Journal). 

Click Options and make sure it's selected for GUID. 

When it finishes continue the Mountain Lion installer. 

Since you already had OSX installed on your hard drive you may be able to just erase it and install as well. Either way the above method will definitely work.