There are basically two groups of database people - developers and DBA. Usually most start as a developer, some later move to DBA. There is another category, BI, which can be loosely or closely related to DB.
Microsoft SQL Server should be easier to get in. However, sql server professionals' earning potential is not as good as oracle's. But you are not confined in one. If you are smart enough, you can develop in both later on, though there is more stuff than you can ever learn in either one. There is a DB2 from IBM, which I believe is the most difficult to get in - not because how difficult the software, but rather the employers who use it.
If you want to go microsoft, get a book which most likely will have a trial version of the software. I used Robert Vieira's Professional SQL Server Programming from Wrox, but it might be too thick for your current situation.
If you decide not to go with a book, get the developer edition of sql server. It costs $50, and has full feature set.