I'm not very good with TurboCad but will try to help you. If you are trying to place a rectangle on top as in attachment below.
Select/highlight rectangle, from local menu at bottom or right click mouse button and turn on Edit Reference Point. Your cursor will turn into a hand holding a button and line. From snap menu or from modes drop down menu turn on snap vertex and show magnetic point. Now go to the rectangle and place cursor at one of the lower corners, the cursor will change color showing that it has snap at corner. Press left mouse button or type the V key on keyboard this will snap and change the reference point to the lower corner. With rectangle selected, Select Rubber Stamp from local menu or right mouse and select rubber stamp. Now move the cursor and rectangle to the top corner. Left mouse click or type V from the keyboard and copy of rectangle will snap to top of rectangle. Make sure to turn off rubber stamp.
Hope this is a help to you.