Then add, subtract, and modify text, graphics, and shapes until your thumbnail is exactly what you envisioned. Place your information into the template by selecting the corresponding area and pasting it in. Upload a snapshot from your video to act as your background. Choose your own Thumb nail free. Step 3 Download your design as an image file straight from the thumbnail maker. Upload and insert your thumbnail into Thumb nail free YouTube video editor and set it as the video cover. Choose one of the customizable video cover templates in the thumbnail maker.