To use the model in your scene you just need to open your project, go to Menu File/Append or Link Object and choose the folder where the hammer was downloaded or saved, choose the file, there you choose the folder Group and then you just click on Hammer Carbon or Hammer Wood. The model will appear at the 3D Cursor. You can move, rotate and scale the object in your scene. I recommend you to use link rather than append. Choosing that you will use less memory in your project, but you can't change the hammer file to another folder, if you choose Append you can move hammer file and your project without any problem, but your project will be heavy. Any questions please leave a message and I will answer as soon as possible.