The Hirobo GPH is a mechanical mix helicopter, so start with setting it up for single servo normal. You can tell if it's a single servo mechanical mix by the pitch arm. The pitch arm looks like a long tray on the top of the front of the frame that can move up and down. You now need to set your servo centers mechanically by removing the servo horns from the servo. Then you'll turn on the Tx and make sure that all trims are centered. Next, you'll turn on the Rx battery to allow the servos to center themselves. Once the servos are centered, put the servo horns back on with the exception of the pitch servo, ensuring that the swashplate is level. Now you'll turn your attention to the pitch servo. Move the pitch arm to center the swashplate on the main shaft, and put the servo horn back on to keep the pitch arm centered. Ensure that when you give left cyclic, the swashplate tilts to the left. When you give right cyclic, the swash should tilt to the right. Forward cyclic, the swash should tilt forward. Back cyclic, the swash should tilt back. Pitch is a bit different for each heli, but generally, the swash should slide down for negative pitch and up for positive pitch (check this by adding positive pitch/throttle and watching the trailing edge of the main blades when the flybar is pointing nose to tail. If the trailing edge points down, you are getting positive pitch. Adjust your servo reversing to get the proper movements.

Next, move on to your pitch and throttle curves. To set up your pitch curve, you need a pitch gauge. If you don't have one, your LHS should have one for under $20. If you don't have a manual, you need to procure one. Hirobo doesn't have free downloads of their manuals, however, I have seen one on another site. I thought I had it bookmarked, but I cannot find it right now. I'll continue looking for it. The manual should state the recommended pitch ranges for each flight mode. Use the pitch gauge to set the low, hover, and high pitch points, then make the curves linear between the points. For you're throttle curves, set them up for the desired headspeed you wish to achieve at each point. Your normal curve should be linear from idle to high (your idle may not be at 0% on the throttle curve). Your idle up curves should look like a "V" or a "U" shape with the low point being roughly half throttle. The exact points depend on the engine, helicopter, pitch settings, and personal preference.

Once your curves are set up, turn your attention to the gyro. Set your gyro up according to the gyro manual, then mechanically set your rudder (tail) trim by turning the tail ball link on the tail rotor control rod until the gyro can hold your tail without the tail wandering much. You'll be able to tell this because the tail will drift in one direction, then when corrected, will drift in the other if your gain is low (rate mode). If your gain is too high, the vibrations from the engine and mechanics will cause the tail to "wag". Once you've reached this point, adjust your gain to where the tail locks in without drifting or wagging. You'll have to re-check this again at the end of your setup. This step is to keep the tail under some control while checking the head tracking.

This should get you pretty close. If you need any more assistance, post back and I, or another member, will respond to help you out.