From the ground (or bottom of the bed frame if you put it on a bed and the bed is more than 3 tefachim from the ground).
I am no expert on tents, but if the tent goes to a point or two points at the roof then you are yotzei. As it states in the first perek of Sukkah, mishna 3: “???? ???? ???? ???? ????. ?? ????? ???? ???? ?? ????? ?? ??? ??????. ?????. ??? ???? ??? ?? ??? ?????? ????.” It seems to me that a simple A-frame tent is no different than ?????? ????.