See OS X- Cannot install on a volume used by Time Machine for backups. You should not have delete the Time Machine application.
If you have 10.6.8 installed then you can open the App Store on your computer. On the right under Quick Links is a link, "Redeem." Click on that. Enter the redemption code you were sent for Mountain Lion. After it is accepted the download will start. If you now click on the Purchases icon in the toolbar, you will find Mountain Lion entered and a progress bar for your download. You should see something similar on the Launchpad item in the Dock, if you have one.
After the Mountain Lion download has successfully completed it will automatically launch. My advice: before you click on the Install button locate the Mountain Lion installer in your Applications folder and put a copy of it in your Downloads folder for safe keeping. Once you have completed the Mountain Lion installation the installer will be deleted automatically. By having your own copy you can make a USB flash drive installer:
Make Your Own Mavericks, Mountain/Lion Installer
After downloading the installer you must first save the Install Mac OS X application. After the installer downloads DO NOT click on the Install button. Go to your Applications folder and make a copy of the installer. Move the copy into your Downloads folder. Now you can click on the Install button. You must do this because the installer deletes itself automatically when it finishes installing.
2. Get a USB flash drive that is at least 8 GBs. Prep this flash drive as follows:
- Open Disk Utility in your Utilities folder.
- After DU loads select your flash drive (this is the entry with the mfgr.'s ID and size) from the leftside list. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
- Select the volume you just created (this is the sub-entry under the drive entry) from the left side list.
- Click on the Erase tab in the DU main window.
- Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
- Click on the Erase button. The format process can take up to an hour depending upon the flash drive size.
Use DiskMaker X to put your installer clone onto the USB flash drive. Wait for the process to complete which will take quite some time.
