Here are some PoCs from the development of BFG & other stuff.

inject_sc.c
Inject shellcode into a running process. 

inject_sc64.c
Same for 64bit. Seems you can not inject 32bit code into a 64bit process.

EnumProcesses.c
Enumarates processes, from MS.

getpidbyname.c
Search for a process by name and returns pid.

hidewindow.c
Hide and show console window.

hollowing.c
PoC for process hollowing.

hello.dll
msfvenom -p windows/messagebox -b '\x00' -f dll -a x86 --platform Windows > hello.dll
For testing dll loading and injection.

load_dll.c
Load and exec dll (eg hello.dll).

inject_dll.c
Inject a DLL into a process.

Notes
Get pid on cmd: tasklist /FI "IMAGENAME eq notepad.exe"
Some parts of the code are from syringe: https://github.com/govolution/syringe