how can i enhance function from this code.

Question

this is an example of that i take from c-sharpcorner i have use it but now i got one problem it how can i determine a particular object is being select and how can i move the object when i have select it i have try it many way but still cannot solve it.hope you all can help me and when the mouse down it draw in a new location.can you enhance from this paintbrush part2 cause i use this code but now i dun know how to continue.thank you for ur help i realli need your help.thank you.this is the source code.if u can put give me the sample code.my program is like rational rose but i did not use drag and drop function.i enhance from this code.i have another question is that can i draw the shape in my cursor so if my cursor move my object oso move.if can hw can i do it. http://www.c-sharpcorner.com/Graphics/PaintBrushinCSharpPart2.asp