richz
If you currently have GDE as your Home replacement app, and want Home++ to now be your replacement app, do the following...
Tap on the Menu key (the one with horizontal lines) while you're in the Home screen.
Choose "Settings"
Now choose "Applications"
Choose "Manage Applications"
Now find GDE, and tap on it. Once it's open, scroll down, and you'll see a button that says "Remove default".. tap on that.
Default Home screen is now removed from GDE. When you press the Home button now, you'll be presented with a screen asking you which Home screen you want to use... along with a check box, which says "Make Default".
If you put a check in the Make Default box, then choose Home++, Home++ will now always open when you tap on the Home screen.
To change icons on Home++, you'll need BetterCut... an app available in the Market, but it does cost a buck or two (worth it, in my opinion)
