Illustrator on IPad - Export selection

Hi I just recently downloaded the illustrator app on the iPad and am trying to figure out how to export with a transparent background. I'm used to doing this through the desktop version but no longer have my laptop. My client is after a scalable logo that can be used as a watermark as well. 

i used to export the selection (logo) as a PNG but I can't find out how on the ipad

thanks