Open the Wix App Market. Find the HTML iFrame element. Click Add to Site.
Open the HTML Settings window. Set Mode to HTML code. Copy and paste this block of code in the code section. Click on Update and close the HTML Settings pop-up.
The iFrame will now contain the YouTube Gallery App. Select the YouTube Gallery App to change the position of your App. Select and drag a corner to resize the App. Don't forget to click on Save and Publish in the Wix website editor to save your edits and publish them on your live web page. The YouTube Gallery App will appear on your live web page. You can edit your App directly inside of the live, published Wix page.
To edit your YouTube Gallery on Wix:
Visit the live Wix web page and select the Settings Icon in the top right corner of the YouTube Gallery App.