why does mavarick only down load partially

To determine if it is actually downloading use Launchpad. You should see a fairly obvious new icon with an associated progress bar. Make sure you check every Launchpad page by swiping left / right.

If it's paused, click the icon to restart it.

Once it completes the icon will appear in Applications and Launchpad, it's just easier to find in Launchpad.

When it's finished downloading it looks like this:

If it really is not downloading read Mac App Store: How to resume interrupted downloads

1. Open the Mac App Store.
2. From the Store menu, choose Sign In.
3. Enter your Apple ID and password.
4. Click Purchases to get to your Purchases Page.
5. Click the Resume button next to the app name.