This nice video tutorial by Greg Zaal at Blender Nerd will teach how to make a simple 3D model with Blender 2.5. Though the model is simple, with this tutorial you’ll learn how to use arrays, modifiers, how to make an UV map, apply textures and render the final model, making this tutorial well suited for beginners.
Please note that some of the techniques explained in the tutorial will result to making a high poly model, as is the case with the corrugated iron cover. While the final result may be too expensive in terms of prim usage in Second Life, it is however interesting to understand how to accomplish the resulting model. You are therefore advised to learn and adapt for your needs.