how can I use normal map for terrain

in unity terrain now I want to use normalmap+ texture unity can do?

Yes, "unity can do". I'm not sure if it supports normalmaps, but you can always convert it into a heightmap (which Unity does read). You can then paint up to (I think it's) 4 textures onto the terrain.

Read this for more information, and next time, ask a better question.

http://unity3d.com/support/documentation/Components/script-Terrain.html

you could also try messing with the base shader for the terrain splats. Its set to diffuse but it could be bumped diffuse, I think.