I was weaned on dBase III+, but I moved to Foxpro, then on to Visual FoxPro.
That's what I would suggest you do if you're planning on doing any serious programming.
dBase III+ is fine for simple things, maybe refreshing your prior knowledge, but since it is a DOS based appilcation you will start experiencing problems running it on newer OS's, not to mention the many limitations compared to newer technology.
I'm somewhat familiar with those, but I've never used either one. They are both rather outdated and limited products.
For a medium to large database management system, VFP is unmatched in ease of use, speed, interopability, and system design.
For larger database files (>2gig), something like SQL or Oracle would be better suited.
If all you're wanting to do is learn some basics, start with the dBase product. It will be a smaller learning curve should you decide you need a better product. But don't bother with Filemaker.
Also, besides this forum, there are many other VFP forums where you can learn from.
One of my favorites is tek-tips.com. There are several VFP forums there.
For more, go to my website: http://www.davesummers.net/foxprolinks.htm and take a look at some of the links I have posted.