I don’t know how to paint this texture please help me
What do you mean by painting this texture?
I mean this diffuse texture process for making, Make use of photoshop ?Or use zbrush?
Any thing will do or U may use crazy bump if U like .
Ah!!! You want to generate a normal map from that diffuse texture?
I use Quixel NDO for that. Allegorithmic’s B2M works well too.
I think Xnormal is free and can generate normal, AO and displacement. http://www.xnormal.net/