I’m trying to add a texture to a mesh that I’ve imported. In this new version, there is no materials tab as there was before in the Mesh Details. When I looked at how this was done through the tutorial, the texture was applied via an element in the LOD. Unfortunately, I haven’t the first clue as to how to add an element to the LOD.
The elements are automatically generated based on the imported geometry. A simple model without LODs and a single element should give you a LOD0 category in which you can add your material to element 0.
If you want more elements you have to define them in your modelling package. In 3ds Max this is done by assigning multiple material IDs and a multi/subobject material. Other modelling packages probably have similar workflows.