Hi 8604...I don't think you can on the email app. I believe this will need to be done on your email server on your PC for it to appear on your iPad. Perhaps others may know of a different way.
Also:
Welcome to the iPadForum! This Forum offers so much information related to the iPad (original-New), Acessories, Apps, Help, and Apple News.
The iPadForum also includes a Regional Ipad Group for international users across the world. This is a wonderful area to "find" members from your own country. Regional iPad Groups
You can create new folder in the Mail app if you have an IMAP or Exchange account It is not possible with POP accounts. I've tested it with iCloud, Yahoo, and GMail (both IMAP and Exchange setups).