Yes - absolutely. To add custom content (i.e. text, images/banner, etc.) to your confirmation email you will need to;
- login to your event
- select 'Build'
- select 'Tickets'
- select 'Ticket Settings'
- in the field titled 'Confirmation Email Message', enter your content using the rich text editor
- select 'Save' when your done
Check out this sample confirmation email graphic to get an idea of where the content above appears.