This is an easy way to make grass. Has similar methed as my sky tutorial.
Start off by selecting the line tool.
Set it to maximum.
Start making vertical lines not straight but have variation in it. Not all the same way.
Now go to a lighter colour green.
Set line thikness to 4.
And go just above the thicker lines.(photo)
Use same method.
Dont forget Variation!
Now go to ever more lighter green and repeat step 2.
Let the ends stick out a bit
Now set the line tool thinkness to 1.
Transperancy to 60.
Change colour to darker green.
Start off from bottom and make allot straight lines check the photo.
I zoomed in so you can see it better
Now go to a bit lighter and repeat step 4.
But use this in the middle.
Now a very light green colour. Same mether at step 4 and 5 but use these above.
Now go to Air Brush and select 6 points.
Set to colour black ans transperancy to 10.
Make some shadow beneath the grass(photo).
Thats it!! ^^
Now you can add anything you want to the picture :D
Good luck grassing!