Q: How do you save a pdf that you have downloaded to an iPad 2?

As long as you have an app that is compatible with PDF's, yes you can save them to the iPad. You can use DropBox, iOS File Sharing, email and some file transfer apps to move the files back and forth from iPad to computer.

Search the App Store for PDF apps. There are many of them available. I like Adobe Reader. It is free, and it will annotate, highlight, sign pdf's, read form fields, create folders, rename files, etc.

Some interesting reading here.

iOS: About File Sharing - Support - Apple

https://www.dropbox.com/ipad

This is a PDF in my Adobe Reader App. Use the same action icon (tap the arrow) that you use to email them, but select Open In and when select that option, you will get this window that you can swipe through to select DropBox.

Helped me too Had been confused.Thx