i cant make work spawn protection

i've put it in different values, and restarted server too, but still no spawn protection, i've read to use world guard but it's not listed in the mods, what can i do?

i tried with no op account, so how do i use world guard on the server?

omg i restarted again now and it worked, i think is because before i was changing values and then restart, now i stopped server, changed value and then started it