How to create Detail texture And height map texture

Can anybody please help me. How to make Detail texture and height map texture for my grass texture. What i want to achieve is realistic feel for the environment. And found in the unity documentaion that i can achieve this by Diffuse Detail or Parallax Diffuse. So i searched for making detail texture and height maps texture. Please suggest or tell me any softwares(photoshop or gimp or anything) to make these textures. Please help me.

I made a bump map for my texture ( bumped Diffuse) but accidentally used it in Detailed Diffuse and actually looked better. SO try making a bump map. (photoshop, desaturate, invert). I think if you have large areas of grass that may be expensive and the mip mapping will blur away this detail at a distance and you may see a noticeable cutoff where this happens