Turrets
Flame Turret
You can make a flame turret if you have the permission "fortification.turret.flame". To do so place a sign on the block type defined in config (netherrack, id 87 by default). The first line must read "Flame" (no quotes, not case sensitive) second line is "[Turret]" (again not case sensitive and no quotes)
When the sign is provided with power (via redstone) and the ground on the opposite side of the netherrack is level, fire shall appear up to 5 spaces (or whatever you define in the config under flame-turret-range) out from the netherrack (fire will not pass through solid blocks and can not appear in midair).
Web Turret
You can make a web turret if you have the permission "fortification.turret.web". To do so place a sign on the block type defined in the config (default is lightstone). Works just like the flame turret except the first line is "Web" (no quotes, not case sensitive). Unlike flame turrets, web turrets do not fire in a line. They fire a shot centered at the web turret length, 9 web total is placed around this spot. The web vanishes after a set amount of time (default 10 seconds, adjustable in config file).
Arrow Turret
You can make an arrow turret if you have the permission "fortification.turret.arrow". To do so place a sign on the block type defined in the config (default any block type). Works just like the flame and web turret except that the first line is either "Arrow" (no quotes, not case sensitive) or left blank. As their name implies, arrow turrets fire arrows when power is toggled to them.