uModeler uses a ‘slot’ system to add materials to an existing object. Each slot is assigned a keyboard shortcut to apply the respective material to selected faces.
When using a material with an image texture applied, you’ll need to move and scale the texture to get the desired result. Texture mapping is refered to as UV mapping in modelling software. For an introduction to UV mapping…
We exported the model with the current textures intact. If you’ll be exporting a model for use with other software it’s usually best practice to texture models in the destination software. You may run into unexpected issues with materials when exported from umodeler and imported into other sofware.