[Help] Entities

My question is, if there is a tutorial to create Entities …
my goal would be to create an Entities (later I will use as ammunition in a SWEP), which transforms into a skeleton to the touch. like HL2 EP2
if there is any tutorial or application that can serve me for this, I would be grateful …
from already thank you very much!
PD: if the Thread is not placed here please let me know!

This thread should’ve been placed in the Questions subforum. Also, I can’t understand what you’re asking for.