Hi
FreeCAD is being developed with new feature etc. at an amazing rate. If you don't tell us your exact version "help about FreeCAD" and your exact operating system and its version, and how many bits, 32 or 64 then depending on what exactly is your question, you dramatically reduce the chance of us being able to give you a sensible, or even correct, answer.
If you are on Linux using the daily PPA with its automatic daily update or if you are on SVN version, or if you are on a recent enough Windows version, and manually keep it up to date (silly Windows!) then the following is correct: -
It is not what you have asked for but some of the following may be helpful for you.
1) Go to the view menu in FreeCAD and tick the tick box next to toggle axis cross. It puts a second axis cross in the middle of the page at position 0,0,0.
2)Also just select the item you want to know the position of, then look at the bottom of "cobo view", click on "data" tab at the bottom, then click on Placement and it will show the position and orientation data, which you can then adjust to move an item around the screen. By default thing are usually created at 0,0,0. But you can send them anywhere, and rotate them in any axis.
3)Also in the "sketcher" or editing a sketch in PartDesign, you get a 2d grid while you are actually editing the 2d sketch.
But as I don't know what version you are running I can't tell you which if any of these functions are in your version.
good night
Jim
