I have been trying to do some texturing watching a YouTube video and in that they are using Blender 2.81a. However, I cant afford it as my computer doesn't have the required graphic card and processor (can't buy a new one for this because I am not a professional, just a beginner). So I have been using 2.76b as it is the one which works best in my computer. When I was making this cube, there was a need to use Principled BSDF node ( the youtuber said it is important to use that . But I cant find the Principled BSDF node in my device ( I tried it in cycles render as was told by someone on the internet but there is no option to select Principled BSDF in cycles render too ) . Please help...
This is a basic standard material nodetree.
If you have a texture into the base color input of the Principled BSDF, plug it into the color input of the diffuse shader.
If you have a roughness value or texture, set it in both roughness input of diffuse and glossy shaders.
If you had something plugged into normal input, plug it into all 3 normal inputs of nodes.
If you had metallic set to 1.0, use two glossy shaders with different roughness value instad of one diffuse and one glossy.
If you had transparency set lower than 1.0, add a transparent shader and a mix shader.
More complicated materials need SubSurfScattering, Anisotropy, Transmission, but Diffuse and Glossy are the basement.