Step 1: Browse for the theme you want.
Step 2: Click the theme then you will see the code on the right side.
Step 3: Click the code box then press CTRL + A (Windows) or Cmd + A (Mac) on your keyboard to select all of the code at once. Right-click on your mouse and copy.
Step 4: Go to Customize Theme and click on Edit HTML.
Step 5: Delete your existing theme code by using CTRL + A (Windows) or Cmd + A (Mac) on your keyboard to select all of the code at once, and then press Backspace.
Step 6: Paste the code that you’ve copied.
Step 7: Click Update Preview at the top and then Save.