Help with height map please

Hi guys
So I am trying to create terrain in blender then import into unity but failing totally. Anyone have a upto date (2.7+) tutorial link for doing this o r can explain the steps if they have time.

I tried to follow a tutorial that then exported as a raw map which turns into 100 toothpicks.Where do i set the heightmap resolution.

Steps i did

created a material made shadeless.
Created a texture.
Selected blend
selected vertical
selected color clamp left color black but alpha changed to full 1
changed x,y,z all to z
pressed N and put in dimentions for some reason its in 1000’s is that for metres? does not say what the unit used is(is this where the heightmap resolution is if so i need to make it 513x513 would that be 513000x513000?)
then exported to unity where it becomes a row of toothpics regardless of what the terrain is.

So i tried to create a color map and paint in B/W to see what happens.
create a texture map 513x513
this is the blender image and what it looks like in unity

Ok figured it out was putting the actual terrain height in the height field in unity instead of the resolution size.