There are two kinds of edit that you can make. one is to correct the poor data and another one is me correct the location. Remember, every edits are making in Google map maker.
Edit a place:
Correcting the poor data
1. Right click on the place you wish to edit.
2. Click "Edit" then select "Edit this place"
3. Fill add more information or correct it in the left hand panel.
4. Give some reason and comment for this edit to support your approval
5. Click "Save" to finish your edit.
Move a marker
1. Right click on the place you wish to edit. choose "Find near this point"
2. Click "Edit" then "Move location"
3. Drag to move the place to the correct position. use satellite view to make sure your moving is correct.
4. Click continue and verify the details.
5. Click "Save" to finish your edit.