ok i need help with my collision... I want to make a normal field, with a line in the center of the screen, the ball can only land on top of the line...
It cannot jump through it... Or better yet, how would I do collision in general? Help!

Just so a ball doesn't fall through a line?
I have no idea of to what extent the advancedness of what you want is... But whatever.
If assuming that's what you want, but I might be wrong
Just do something like
If y-sprite height<25
Y++
End
If the line is at 25 y axis.

For collision in general to check if 2 things are touching I usually do
X is x of first object
Y is y of first object
A Is x of second
B is y of second

If abs(X-A)<6
If abs(Y-B)<6
Stuff
End
End

That'll check if if the 2 objects are less than six pixels apart.

Oh yeah. But if you're holding the screen upside down...

If you were Holding the screen upside down and the object was coming up from the bottom of the screen and the sprite was rotated 180°. Then it would work!