Inject dll into process PID

Good evening, I spent a few days looking for the subject I mentioned in the title, "Inject dll in PID" ie "inject dll in process pid" '-', in case I have a difficulty in making this injection code.
For example...
This is the process -> "CombatArms.exe"
This is the PID -> "2000"
*(PROCESS, PID, DLL)

I want to inject the dll into the process PID and I do not know how to do this line of code.
*
If anyone can help me, thank you!