If you would like to create a row of pictures in your banner, you will need to use a photo editing program to do this. We suggest using PicMonkey.
Before you get started, you will need to look at the dimensions of the banner area of your style (this will be displayed at the top of the dialog box when you hover over the banner area) so that you can create your banner to be the proper size.
Once you have designed your banner, you can upload to your File Manager. Please check out this tutorial: Adding a Banner for more information on how to add a custom banner to your site.