Hey, I’ve been trying to add 2 materials to an object in UE4 for a while, I ended up finding a tutorial on how to do it using Blender and later importing it into UE4, however when I do so, only the color will change, for example if I put on a Rock material, it will only apply the color of the rock. I need help with this as soon as possible please, thank you 
You need to set up UV mapping in Blender for your mesh
In Blender select some edges and do Mark Seam, then select everything and do Unwrap. There’s also some other useful options like Smart UV Project that automatically unwraps using angle settings, Reset that sets the UVs for all faces to 0-1 so you have them overlapping, Lightmap Pack which packs things flat with a margin (useful for a lightmap) and finally Follow Active Quads where you select an active face and unwrap one face at a time and end up with UVs in a strip, really useful for stuff like hair or roads.