Select the whole model, or one part of it by using the select tool to select 1 or more objects, then after they're highlighted red, go to the Materials tab on the right side (if you got your control panel on the left, then go to the Materials tab on the left), then hit the button that says <none> and browse for a texture in Add-Ons/shapes and it should then apply itself to the model, to fix the texture, leave the object(s) selected and click the Window drop down menu on top and click Texture Coordinate Editor and click the button that says Front (if it doesn't say front, it should say left, right, top, bottom, or back), click one of them and hit Remap to change the way the texture is, and use the Move, Rotate and/or Scale tool in the window to fix it up
Hope you can understand that