Looking at the last few lines, I see that you are a bit confused about 'went' and 'been'. Well, as far as 'visiting' or 'going' to places is concerned, 'went' talks mainly about a one time event whereas 'been' talks about going and coming back.
I've just been to the bank -I went and came back from the bank.
On the other hand, if you say...
I just went to the bank- talks about your presence in the bank (probably a one time event). For instance, you tell your mom at home that if your friend comes asking you, she may reply that you 'just went' to the bank.
In the same scene, when your friend is waiting for you and you arrive at your home, you can tell him that you have just been to the bank. So, 'Just been here is -went, finished the work, came back'.
Remember the nursery rhyme? Pussy cat pussy cat where have you been? So, here, the cat had gone and came back! :)