I mean it depends on your background. But luckily you are gonna want to be familiar with MS products for basically any job you apply for. It's something you may not get in school, but you are gonna want it regardless.
First step is to get a copy of Office 2010. You will want to be familiar with the ribbon setup.
I don't really know any formal courses or anything, I don't typically go that approach. I just use the internet to find stuff out/teach myself. This site was very helpful for reference for me: http://www.ozgrid.com/Excel/
Just go through each of the sections and study it.
What I would do after that(and what I still do now) is just go through forums and either help people solve problems or just read through others solutions. Take your time and focus on the simplest, most efficient way to solve things. Brute force is not your friend.
If you do this enough you will pick up a ton of extra skills. This is going to be true of just about anything, use this advice for other stuff too.
If you want to pick up math/other science tips in this way, I used to frequent this forum quite a bit: http://www.physicsforums.com
. Traffic may have died down a bit but it seems pretty active still.