Install or Update Your Present Theme to Twenty Twelve
It just takes a few clicks to install WordPress Theme Twenty Twelve or update and switch to it from a previous theme.
Steps to Install or Update
1. In the Dashboard go to Appearance.
2. Click on Themes when this label pops out after your put your mouse over Appearance.
3. Under Themes click on Install.
4. Type Twenty Twelve in the search box that shows in the upper left of the screen.
5. When Twenty Twelve appears click on Install under the picture of the theme.
6. Click on Manage Themes at the top of the page next to Install Themes.
7. You’ll see that theme Twenty Twelve shows now at the upper left with labels under it for Customizing it.
8. To customize it click on the labels or use the menu labels on the left side of your Dashboard.
9 There may be differences in the numbers of widgets from your previous site so check your widgets. You can also switch back to your previous theme by selecting it in the Manage Themes screen.
10. Updating from theme Twenty Eleven is the same as the above steps. When I updated my website from Twenty Eleven it went very smoothly.