How to add spawn icons?

Excuse me,
could anyone provide the information of how to add you own spawn icons so that they correspond with the object in the (Q) menu? So many people leave this out and i have been pondering the question. I always considered this to be the easiest of sorts, but what do i know. I assumed that the community captured screenshots and utillized them. Is there more to it? Can i just insert its contents into a selected folder? I read the faqs and etc… and i hope i followed all the procedures. I really didn’t know what to place this thread under. I don’t recall viewing a ‘General Mod’ question data base for Gmod but if i am wrong please don’t hesitate to correct me.

Maybe you didn’t undertand my question since it wasn’t too broad. When you open the (Q) menu and chose a weapon, npc, and/or entity it usually will have an icon. I want to know how to make my own icon and/or use it ingame for my object. Alot of mods usually don’t provide an icon so i would like to add my own.

If you mean for props, they’re automatically generated by Garrysmod.

I meant to establish that some installments (mods) don’t provide icons. How do i create and insert my own?