Crew Management Overview
 

Here's a quick and dirty "How to spend Promotion Points". :O:

First open your crew management screen. Either the little crew icon in the top right or press "H" then click Crew, the left most tab. Here you'll see your captain and crew.

As you can see here I have 1 Promotion Point to spend and I've lost all my crew morale since I loaded a save. :( You can also click the little Iron Cross icon in the bottom right of your picture to see what, if any, silently awarded medals you've won.

http://img716.imageshack.us/img716/5931/crew1y.jpg

I think I'll give my Cook the ability to cook a special meal so that I can gain back at least some of that lost morale. I'll click on his picture like this:

http://img355.imageshack.us/img355/4193/crew2.jpg

Oops! Looks like I don't have enough points to train the Special Meal ability. But here you can see the other things I could train. Hover over a box to see what it does.

http://img242.imageshack.us/img242/641/crew3.jpg

I guess instead I'll give my point to my torpedo guy to make him faster at reloading torpedoes. I'll click Discard on the Cook's page and go back to click on the Torpedo Man's icon. Here I can click on the first icon there, highlighting it to make him reload tubes faster. Click APPLY if you're happy with the point spending.

http://img205.imageshack.us/img205/1508/crew4w.jpg

Once I'm back at the crew screen I can click the little circle next to my torpedo guy to see that I've increased his ability a bit, as shown here.

http://img130.imageshack.us/img130/3325/crew5.jpg

Hope this helps!