To give your post or page a sleek, professional look, you can add a Cover block.
Get started by clicking the + Inserter icon 
at the bottom-left corner of the screen and select the Cover block from the blocks list.
It will look like this:
Once you insert the block, you have some options. You can either pick a background color by tapping on the color circles or you can insert a background media. If you select the option to ADD IMAGE OR VIDEO, you will then need to select where you would like to add the media from:
Choose from Tenor allows you to search for GIFs provided by Tenor. (In the iOS app, this option will be Free GIF Library.)
Once you select either a media file or pick a color as your background, you can also add text on top of it
When you have selected an image, you can tap on the “tools” icon to either replace the image with another one or edit the image you added.
