Every visible object in the game will have a button called 'model' on its base form on the Geck. Click it and note the file and path name. Then load the Geck with your own mod and create a new object of the same type as the FOOK one. Just set all the fields on the objects base form to the same values as you saw on the FOOK object.
Alternatively, you can create a new blank mod, then load it as the active file along with FOOK and just edit all the FOOK objects and save them with a new ID. This will place a copy of the FOOK object into your mod with a new name. Then close the Geck and open it again with only your mod. Now all the copies you made will be ion your mod, but with a different ID than the FOOK versions. Sometimes this will make thing a bit tricky, like if there is a script attached to an armor object for example. When you change the name, the new object in your mod will be looking for the old name of the script, so you'll get a warning and the script field will be blank in your new armor object. So you will have to reattach the script (that has a new name) to your armor (that also has a new name).
Alternatively, you can do this with a utility called FO3Edit and 'copy as override' the selected records from one mod into another. But all of this requires lots of learning on your part. To be honest, if you haven't gone through the 'My First Vault' tutorial on the Geck main page, you should so you can get a good basic understanding of how everything works. I doubt anyone is willing to hand hold you through all of the steps you need to learn as everyone has their own projects they are working on an the time required to teach someone all the basics is pretty big. I know for myself, I must have spent 40 hours on my own learning stuff before I actually had a shimmer of an idea of what I was doing. I mean no disrespect.