Hi abc123pjm,
It appears that you are asking about filling in an region of a 2D sketch in a part file (*.ipt). I think this is a bit different than what everyone thought you were asking about, due some confusion over your use of the term "drawing".
What you show is not considered a drawing in Inventor, but instead it is considered a sketch in a part file. A drawing in Inventor is an *.idw or *.dwg file, that you use to create views and annotation to a model file, such as a part (*.ipt) or assembly (*.iam).
There really is no way to color fill a region of a sketch in a part file that I am aware of.
Can you explain what your end goal is? And then maybe someone can direct you to the correct tools.
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com