I can't really advise because I'm fairly new to the game myself, but one thing to do would be to look at job adverts and see what skills they're asking for. Also try to work out what sort of DBA you'd want to be (Production, Development, other). You may not figure this out until you have a bit more experience under your belt, though; http://www.brentozar.com/sql/picking-a-dba-career-path/
There's no substitute for practical experience, but you can download the Express edition of SQL Server legally and for free here
so you can work on it on your own computer. It doesn't have all of the functionality of the paid-for versions but you won't need them yet.
There are even free databases you can download to work with, containing sample data. Adventureworks
is the SQL Server 2008 version.
Finally there are loads of free e-Books
on this site. Some of them are quite advanced so you might want to hold off for a bit, but the Backup & Restore
book is very useful and I would recommend that. You can download it for free as a pdf, or put it on your Kindle/iPad/whatever.
Hope that helps.