To apply a texture to a 3D model, you first UV-unwrap the model (convert its 3D surface to a 2D "map") and then align 2D texture files (like images or patterns) to this map using 3D software.
UV unwrapping prevents texture stretching, while tools such as Blender or Substance Painter let you adjust scale, rotation, or opacity to fit the model’s shape—adding realistic details (e.g., wood grain, fabric) that make the object look authentic.
For beginners, start with simple models (like a cube) in free software (Blender) to practice UV unwrapping and basic texture alignment—this builds foundational skills without overwhelming complexity.