To create a Collection, from the dashboard click 'Manage' and select 'Collections' from the menu. This will bring you to the Collections page where you can click 'New Collection'.
This brings you to a page where you will create a new Collection.
You can give your Collection a name (this will make it easier to find later). A Collection is your own workbook of selected styles and colors from a base catalog. Select the base catalog you would like to work in and click 'Create'. This will open up the Collections Builder and you can start building your assortment.