Visit the Appearances > Themes page from the Cmslooks admin dashboard. Here you can see all the available theme lists. Here the default theme is available.
To add a new theme click the Install Theme Button.
Now you have to upload the theme zip file. Then click install and wait for some time. After successfully installing you will see a new Theme is added to the list.
In the Theme List you can see a new Theme is added.
Now you have to activate the theme to use it. Click Activate. ( If the theme is licensed Give purchase key to activate. )
After the Theme is activated, You can work with the theme.