Not sure what courses are out there these days, but I can offer a few online resources. There is a lot of information right on the Microsoft Access site. There's a training section in the left frame.

And here are a couple of sites that have a lot of tips and help:
Allen Browne's Tips for Microsoft Access
Dev Ashish's The Access Web

However, personally I think it's easier to learn data design and structure if you have someone to talk things over with. Maybe there's an inhouse local college course or something like that near to you? Or maybe an online course that has an instructor.

If you stick with books or tutorials, look for something that explains "normalization" and then make sure you follow 1st, 2nd and 3rd normal forms. This will help you figure out relational tables. Here is one site I found through Google that explains it - TechTrax. I think it's also explained at the Microsoft site above.

Anyway, hope at least some of that helps.

Deb