can I have multiple icloud email accounts?

Apple is reserving and @icloud.com address as a second address for all existing iCloud users, as explained here: http://support.apple.com/kb/HT5441. It won't go live for a few weeks (see second paragraph).

iCloud has a feature called "iCloud mail aliases" which allows users to create up to three so-called alias emails. Each of these is a completely separate email address which forwards email to you and lets you send email from it. Unfortunately, there's no way to have two separateaccounts in iCloud, but this may prove useful to you anyway.

To set up a new alias, go to https://www.icloud.com/#mail and open Preferences, accessed via the gear icon in the top right. Under the Accounts tab, click "Add an alias…" and fill out the desired settings.

I'm trying to do this and for some reason it keeps telling me "this alias is not available". What does this mean exactly??

Doesn't matter what I enter, tells me the same thing! grrrrr