Let say you want to put a pin on an exact location or item on a map. Here is an easy way to do it:

Go to the zoomed map and find the sector you want.
Right click on the sector and select center.
Now zoom out to the world map.
You will see a gray area where your select box was.
If you center the cross so the highlight is exactly over the gray area the cross will be on the sector.
Press your pin key, you have exactly marked that location.

I like this advice, but what/where is the pin key? I can't see anything of the sort.

You have to set your own shortcut for it on the options page.

to clarify that just a bit, Options = Settings.

keyboard shortcuts can be found on the "Settings" page, directly below the "Play Global Triumph" button, not the Profile Settings page.
It took me a while to find it because I was looking for Options, not Settings. (And was also looking through profile settings too)

After discovering that Settings page, wow. so many ways to set up hot keys, virtually for every action in the game.

Thanks again.