Can't answer the ph level part, depends what you're going to be growing. And some veggies, particularly root ones, don't like manured ground.
Otherwise, generally, incorporation of well rotted composts such as garden compost, composted animal manures, leaf mould, spent mushroom compost, anything humus rich like that, will be of benefit.

thanks you, im growing grass

If you mean a lawn, don't worry too much - just prepare the area properly by digging over, removing all perennial weed roots, level, walk all over it on your heels to press it down and get out soft spots, then relevel, rake up. At that point, sprinkle Growmore on the ground till it looks like thin, sparse snow, then lay the turf.