1. Go to Communities > Special Events > Friends Asking Friends > Kintera Thon
  2. Hover over your Thon name, then choose Webinfo Checklist
  3. Select Fee Structure
  4. Find the section labeled Registration Levels
  5. Click Edit on the registration units you want to add the option. 
  6. In the Pop up, add the appropriate t shirt sizes and information
  7. Save