Gather up as much Energy as much Energy as you can, (the exact type of energy does not matter, as long as its not Elemental). After you believe you have enough gathered up release it into the Area of you wish to increase the gravity of (the smaller the Area, the easier it is to increase). Now after the energy is in that area, focus on it and make it be effected by Gravity, then move the energy faster and faster... as its doing this put your hand into the effected zone and see if you can feel a difference. Try this on a weight scale as well.
Fill the Area with energy, notice how the energy is being effected by Gravity, then Slow the energy down until it stops completely, its not moving up or down at this point. Put your hand in the effected area and see if you can feel if it is being effected, also try this in an area with a small object there on top of a scale, something that weights a few pounds, so it shows up on the scales, see if you can effect it.
Fill the Area with Energy and let it be effected by Gravity, then Make it slow down, stop then reverse and move up at a slightly faster speed then it was moving down. Again, try this with something fairly heavy on a Scale.