how to record the actual longitude and latitude of point on google map?

[#1]

In the following picture I'd like to place some thumbtacks (as you can see on the right side) on a virtual GPS map,

Effects are listed below,my questions is ,after I placed those thumbtacks (actually these are just vectograms),how to record the actual longitude and latitude of those point where they located?  Thanks a lot!

[#2]

any ideas?