There are some three things that you can do using the typical e-book reader (such as the Kindle, the Nook and the iPad).
The first thing you can do using the typical e-book reader is, of course, to read books (and newspapers and magazines). This is the primary purpose for which the devices in question are designed. Their screens are specially adapted for the book-reading function. Some of the devices in question are designed purposely to facilitate book reading (the likes of the Kindle and the Nook). Others are designed for other purposes, but with the e-book reading functionality integrated (an example being the iPad).
The second thing you can do using the typical e-book reader is browsing through websites. Most of these devices come with full-fledged browsers that you can use to browse through the websites you fancy.
And the third thing you can do using the typical e-book reader is sending (and receiving) emails. If, for instance, you want to access Gmail on any one such device, you start by launching the e-book reader’s browser. Then you enter the Gmail website address (mail.google.com). Then you proceed to log into your Gmail account. If you have difficulties in the process, there are plenty of sites and forums where you can always find free Gmail email account help.