Follow this video for easy step-by-step instructions:
Step 1: Log in to SiteGround's Customer Area
First, log in to SiteGround's customer area by going to www.siteground.com and clicking on the “Log in” button on the top right corner of the page. Enter your username and password to access your account.
Step 2: Use Existing Domain
Select the option to use your existing domain (from NameCheap). Fill in the domain name and click continue.
Step 3: Set up site
Click start a new website, then click WordPress. You don't need any add-ons at this point. Click finish and Siteground will install WordPress on your site.
Step 4: Log in to Your WordPress Dashboard
Once the installation is complete, you will be taken to a page with your website's login details. Click on the “Admin Login” button to log in to your WordPress dashboard. Here, you can customize your website, add new pages and posts, and install plugins and themes.
