@david.rambo78
Hello David! Thank you for installing the mod, I'm happy to hear your son is interested in the addon. (The addon currently produces a 'console error' but this shouldn't affect gameplay at all. An update to fix this issue will be released soon)
For your son to be able to use the animatronics, he will have to do the following;

• Install the addon
  
• Make sure it's enabled (addons are enabled by default after installation and will only disable when told to)
  
• Start a single player game via the main menu in any map
  
• Hold Q to open the spawnmenu and navigate to either 'ENTs' or 'NPCs' at the top (pressing F1 keeps this menu opened)
  
• Click on the Five Nights at Freddy's category to the left (the name will vary judging by the addon you've chosen to install)
  
• Click on the now visible 'spawnicons' of the animatronics to create them
  
• They will spawn directly to where your son is facing -- best to look at the ground far away
  
• Let go of Q or press f1 to close the spawnmenu

If he's chosen to spawn them through the ENTs tab, they will be idle, and teleport closer to the player when out of sight.

If he's chosen to spawn them through the NPCs tab, they will chase the player.
This next step is only for the NPCs, the ENTs do not need this process
If your son notices that the animatronics are not moving, it's most likely due to the fact that the map he is playing on needs a 'nav mesh" (The maps gm_construct and gm_flatgrass that come with the game shouldn't have this issue, as they already have nav meshes)[/u]
For the animatronics NPCs (not the ENTs) to move, you should read the guide here.
Goodluck! I hope you have no issues with this process.

Here is a list of all of the FNAF related addons that my brother and I have posted, incase your son is interested.