The large pics in the custom library (that have the play buttons on them) are already
perfectly sized (width 790) to fit onto Lead Capture Page #1.
You can manually adjust the pic size by changing the numbers in the 'Width' box. (seen at 1:08)
1st RGB: Area surrounding the form fields and submit button 2nd RGB: Submit button 3rd RGB: Color of the submit button when you hover over it 4th RGB: Large background area covering most of the page (rarely used)