I don't know how to ADA

Hello DV, i had being trying ADA over 2 months, but recently
i've been more confused, and i came to conclusion that i don't know how to ADA.
While i am on computer playing games i forget everything around my surroundings
and just keep playing, but when i get out of computer i try to force my mind being aware of my surroundings.
i feel my feet as walking to another home division, i try to hear, smell and feel.
but i think my mind doesn't support all this at the same time and i just end up losing my concentration, i thought
if i could notice all of those things my awareness time would raise, but it's happening the inverse.
but if i am not supposed to feel my surroundings at the same time what am i supposed to do?