You’ve got two choices. Either build the shader in a procedural manner, or just slap an image texture to it. For image textures there are websites like Poliigon that have already all sorts of textures set up to make your job easier. Building the procedural shader from the ground up takes a lot of effort and node magical knowledge, that is something you can learn but it will take time. You’d think a realistic shader node will be super complex full of nodes, but I remember from Bartek a lesson where he showed that isn’t the case, it’s easier to cheat and the result is the same. Also lighting gets a huge roll on how your materials look, it’s the light interplay that will inform you of what the surface is, we often forget that.
