OK...I don't know for sure but I suspect the D3200 does have a dot confirmation type deal.
Here is the most important thing for you to remember about manual focusing any lens - not all of them do this automatically either - ALWAYS open the lens wide and focus...when you have the dot then stop it down a stop or two or whatever depending on what sort of DOF you want to work with is (and if you are going to stay wide open you better be damn good with the dot alone
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The reason why is because it does two things - it increases the light that gets to the viewfinder, it reduces the depth of FOCUS (which is a different deal than depth of FIELD), and it helps you to pinpoint the focus on the critical part of the picture. Stopping down then increases the depth of field which ensures that your image will be in focus in the desired way...stop down greater and you get more DOF.
Just because you have the green dot doesn't necessarily mean you are in perfect focus like you want!!!...the above dogma is very crucial to getting sharp and in focus snaps when manual focusing...it took me literally thousands of snaps to understand this most important manual focusing concept and I am not kidding!