How do I make a custom texture/mesh from scratch

I came across a big problem: I am trying to make a "lava" effect on a sword, but I'm having a hard time of doing so because I need to export/import files from blender and nifskope. I also need to set the data files on nifskope, and I really don't know how to do those. I read the tutorials of custom texturing from a UV map, better retextures, and making custom swords, etc. But I'm not entirely sure of how to open up brand new meshes and choosing collison capsules. I'd be glad if someone could help me with getting started on exporting/importing. Thanks.