There is no RealPlayer app for iPad. You'll need to convert your movies or audio to a format the iPad does recognize, sync them to iTunes and play them that way.
If you're looking for a way to listen to live RealPlayer streams such as those on the BBC site, you'll want to find a native app produced by the organization that created the web-based RealPlayer stream, and use the native app instead.
I presume you want to play video files. If not, ignore the following.
There is an app called "GoodPlayer." If you want to play videos of several file formats, you need GoodPlayer. It is a great app!
On your home page, tap on the App Store icon, then in the upper right hand corner, type in GoodPlayer. Then tap on the app to download it.
When you send video files to iPad, by e-mail for example, tap and hold on the attachment, then you get an "Open in " menu. Select "open in," then GoodPlayer."