i've been wanting 2 use my manual chair but my balance isn't that good in it, what can i do to improve it

Getting your chair set up properly to accomodate your bodyshape/balance would be a good place to start. If you have some friends with w/c experiance or whoever gave/sold you the chair should be able to help.
Good luck!

it is a difficult thing to practice with the permanent, odious slouch and imminent risk of falling over. but............

i practice everyday sitting on the edge of bed with feet on ground. i reach or lean side to side, or do mini 'hoola hoops'- try to rotate waist and hips and keep balance. i put electric stim on my abs/paraspinals 30 min per day to build more sturdiness in the trunk or use that for extra stability while practicing balance.

in my manual chair, i stuff a pillow behind my lumbar region to push my lower back in and straighten back posture- i find sitting upright like this while trying to do functional activities helps and feels amazing. i strap in for safety so that i don't tumble forward.

i'll try it

Don't forget your cusion
There are so many to chose from
The one that stopped my hips from moving forward is the
Jay Duo that has a molded seat pan with a gel pad cushion.
Yes..the gel cushion does split eventualy
Get the palm of your hands as close to the wheel centrespindal as possible
Mines 80mm away
Where your wheel spindle is in relation to your back is down to your abilities
I like a tippy chair setup whitch for me is 50mm in from bottom of backrest
If I didn't have the weight of my legs it woul be at least 50mm out from the backrest
Bottom of my footrest is 65mm off the ground

It's trial and error until you find your setup
As your damage is higher the mine...your setup won't be like mine
It took a weeks holiday with fellow wheelies to find mine.
Ramps, pavements, curbs, rough ground, rapid wheeling, round of drinks on a tray
Don't be afraid of falling out - it will happen

And if bi-peds can't be bothered to get out of the way...run em over