To texture you would need a picture close to or on the angle you want the texture (Usually side-on). The textures can be from the internet as one photo or multiple to be put together in a photo editing program. Usually it would be best to take the picture yourself. Any editing needed could be done in any photo editing program (Photoshop, Gimp, etc..). Below is a sample (tiled at each support) with textures from the internet photoshopped and a normal map.