To create a new version for an existing review URL, click on the Reviews tab, then click on an existing Review card, then click on the Plus icon button, select the Figma frames you'd like to upload (and select the order you'd like them to appear in).

Once you've selected your Figma frames, give it a New Version Label (which will be shown in your Review's Versions dropdown selector, and also user-facing in the web app's heading text when viewing the versioned review link), then click the Create New Version Review URL button to upload your frames and generate an additional version on your review link.

Once the static Figma frame images have finished uploading, you'll be able to copy the new version Review URL and password (or the passwordless URL) to share it with any stakeholders, which will let them leave feedback on your designs via the Commentful web app in the browser.