Trouble with custom models, need tutorial

[Acies]

The .mat file is created upon viewing the model in modelview or ModelEditor, as long as it has a texture assigned within your modeling program. The .mat file tells amnesia where to look for the texture of it. Photoshop has a .dds plugin which will allow you to save your images as the ".dds" format. It is free to download. Why use it? It is far more effective performance wise to have your textures in ".dds" than in ".jpg".

Finally; The staircase has no need of an .ent file, just have it as a static object.

Edit: Save it in the static objects folder. Collision is automatically added to the mesh then.
Edit2: The models looks nice but the textures look awfully stretched :>