iMac Pages document to iPad Pages app

You can email the file and then use the Open In option from the mail app. You can use iCloud if you have it set on on the iPad. If you running at least 10.5.8 on your Mac you can use iOS file sharing with iTunes.

Read this for information on file sharing.

http://support.apple.com/kb/HT4094

if you are using iCloud on the iPad, you can just launch Safari on the Mac, log into iCloud.com, click on the iWorks icon, click on Pages at the top and then drag the file into the browser window. It will then be available in Pages on the iPad.