Firstly, create a folder in the entitybank and call it whatever you want the model called.
Place your .x file in there.
go to one of the other entity folders and copy one of the .fpe files.
Navigate back to your models folder and paste the .fpe in there.
Open the .fpe with notepad and change the relevant details.
Then create a 64x64 image that will let you know which model it is. (take a screen shot in your modelling software and shrink it down in paint or GIMP or photoshop)
Then, make sure all three file are called the same, (you don't have to call it My_Model, this will get confusing for you. I would name it whatever the childs name is)
If you have done this properly, you should then be able to open FPSC and go to the entitybank and choose your model.
Ortu is correct though, this board is only for 3D modelling software related chat as well as serving as a WIP thread.
If you have any questions, you would get more responses posting this in the Models and Media board.
Welcome to the forums!