Sleek is available as a theme extension (Sleek.mbrext) for Mobirise Website Builder, to install it:

1. Download the purchased package of Sleek from your Themeforest account http://themeforest.net/downloads and unzip it. Find the file /sleek-builder/Sleek.mbrext in the unzipped folder. You'll need this Sleek.mbrext at the step 5.

2. Download and install the Mobirise from the officail site - https://mobirise.com/

3. Run Mobirise and select in the left sidebar "Menu->Extensions & Themes"

4. Find and click the "Import" link in the top-left corner of extension list

5. Select the Sleek.mbrext to import the Sleek

6. After the Sleek is added to Mobirise, you can create the website using this theme - in the left sidebar select "Menu->Sites->Create New Site"

7. Select the Sleek as a theme for a new website

8. Click a red "Plus" circle in bottom right corner to start adding blocks to the page.