Operation of DiveComp should present no problem to any diver with some experience in computer diving.
And since nothing you do with DiveComp can hurt your Newton, you should really experiment on your own.

Anyway, here is a possible simulated dive.

Having started DiveComp, I bring up the Prefs slip from the button. We will leave the default settings for now, so I dismiss the slip by tapping on the Done button.

Next I start the simulation by tapping the button once to get a descent rate of 10 m/min.
Simulation speed is x1 (i.e. real-time).

At 8 meters I tap the button once, bringing the dive rate to 0 m/min, so we hover at this depth (we could as well have tapped the button).

Notice the display indicates SAFE DEPTH, and Deco display is blank. We could remain at this depth indefinetely, but we dive again by tapping the button.

Another rest at 20 meters by tapping the button. Dive time is 2 minutes, so far, and Deco display is showing we have 40 minutes left at this depth. Notice also the air pressure in tank is decreasing.
We then proceed with our dive, increasing simulation speed to 2x by tapping once the button and then the button.
At 32,5 meters we hover by tapping the button, and let the simulation run until we reach 15 minutes of Dive time, then I tap the button. We only have 1 minute of no decompression time left, and a safe diver would begin his ascent now. But I resume the simulation by tapping again, and remain at this depth for 5 more minutes, thus entering a decompression situation.
Notice the Status B display indicates NO DECO. No decompression is possible at this depth, and we have to ascend. Notice SAD display appears, indicating we cannot ascend to less than 2 meters. Also, Deco display now shows an Ascent time of 4 minutes. This is the time needed to reach SAD plus the decompression time at SAD (in this case, 3 min to ascend at 2 meters, plus about 1 minute of decompression at 2 meters).
I tap once the button and then when at 19 meters. Now Status B says DECOMPRESSION and Deco display indicates we need 4 minutes decompression, should we choose to remain at this depth. Notice that, since we are already decompressing, SAD has decreased to 1 meter.

I tap the button again to ascend to 5 meters, and here I wait until decompression is over.
Now Status B indicates SAFE DEPTH, and we can finally reach the surface.

Status A now says SURFACE, and Status B shows DESATURATING.
Dive time indicates more than 23 hours for complete desaturation.
Depth display now shows the max depth reached during our last dive, 32,5 meters.
Should we decide to perform another (repetitive) dive, we should first refill our air tank, by choosing Prefs from the menu, and set the tank pressure as desired.
To speed things up, I tap the button several times. In due time, desaturation is complete and Status B indicates OK.