Adding a layer/image over a City

I've noticed that you can't create your own (like drwing on the map) Territories in MapPoint. However, I read in an archive post that you can add a layer or image over MapPoint. I was wondering how you would go about doing this, what format the file needed to be in, and how to affix it to the map.

Long story short, I have a grid (this grid has odd shapes, not just boxes) of San Antonio that I need to be placed on top of MapPoint. This way I can search for an address and see which node in the grid the address falls in. Thanks for any help you can give.

You can add a freeform shape by drawing with the freeform tool on the drawing toolbar.

I beleive there is also an free addin that you can download someplace that let's you add ESRI shape files to MapPoint, but I'm not sure whether you can subsequently do any queries to see what's within it.