For more help on how to install Umbraco see Umbraco documentation.
If you want to use Umbraco Cloud simply follow the steps after choosing a plan.
The installation is a standard Umbraco package installation. Follow the steps below.
Log in to your Umbraco site and go to the Packages section.
Click Install local
Drag in the Igloo package zip file
You also install Igloo theme by going into the Packages section of Umbraco and searching for "Igloo". Once on the package page simply click the "Install package" button
To activate your license go to the package option view for Igloo. Found under Packages -> Installed -> Package options. Follow the instructions on this page and click Register to activate your license. To change your license you can return to this page and enter a new key. This will change the value in the
Igloo.key file found in the root folder of the site.