To use this rocket launcher, you must select the type of Hellstorm Rocket by pressing on one of the rocket icons below:
Next, you must manually load it with any Hellstorm Rockets, by pressing the icon with a image of the Hellstorm Rocket you have selected plus 3 little circles below. The 3 circles will fill in with a color corresponding to the Hellstorm Rocket you choose. Once the 3 circles have been filled, press the icon again to fire (obviously you need to select a target). You can also fire less than 3 Hellstorm Rockets by pressing the icon before it is filled up.
Continue to repeat the loading process and firing process as you battle.
To load a total of five rockets, see HST-2, an elite rocket launcher. You can get the HST-2 launcher fairly quickly through Auction and even cheaply, so it's not recommended to buy this rocket launcher.