Step 1. Select 'I want this file'; Step 2. You will be redirected to Canva; Step 3. Select 'Use Template for New Design'; Step 4. Sign in to your Canva account (or create a new one -- there is a free option); Step 5. Design a new custom banner for your profile by editing the template. 

💁🏻‍♀️ Pro Tip: I'm guessing that most people will interact with your profile on either the web or mobile, so I recommend deleting all of the elements in the file except the profile image markers and trim lines for mobile until you are done. The goal is for your design to fit inside those markers to ensure everything you deem important is visible across all 3 platforms (web, mobile, app).