what do i need to fix
ammonia-8.0 ppm
nitrite-0.3 ppm
nitrate-0 ppm
high range ph-7.5
ph-7.5
what do i need to fix
note: there is a tiger barb and a rainbow shark in the tank right now

The only thing I can add to Ian's answer is that it's possible chloramine is skewing the results. Chloramine is made of chlorine and ammonia, and when treated with water conditioner it is broken back into chlorine and ammonia, then bound into a form that is safe for fish, but still registers as ammonia to a Nessler reagent, which unfortunately is still the most common ammonia detecting reagent used.
Aquarium test kits will probably change soon, because chloramine is being used more and more, and it basically renders Nessler reagent tests useless.
If you suspect you are getting false readings because of chloramine, there is a sure-fire test. Treat some water straight from the tap with water conditioner/dechlorinator. If you get a reading for any ammonia (but usually around 8 ppm), you have chloramine in your tap water and a Nessler reagent ammonia test.

Wow! Immediate 50% water change is needed. That is some high level of ammonia and nitrite. I'm surprised your fish are not gasping for air or dead.
Best bet to get those levels lowered is to do a large water change now (50% and don't forget to add some more water conditioner). Then test again tomorrow. The levels should drop a bit. If they don't drop drastically, then you'll have to do another large water change. Keep repeating the process every day until the ammonia and nitrite levels have lowered. Then you can go back to your usual 20% (or round about) water changes.
Test the water every single day until your ammonia and nitrite is 0.
It sounds to me like your tank was not cycled properly and now it is having a huge spike. Yes, large water changes do stress the fish. But sitting in ammonia filled water kills the fish. The large water change is the lesser of the two evils and the only option at the moment to perhaps save your current fish.
If you don't have live plants in your aquarium, now would be a wonderful time to add some! The live plants will help suck up some of that poison water. Also turn on a bubbler to get some oxygen flowing.
Good luck!

Double check the ammonia. 8.0 is pretty much instantly fatal to any fish, and will even start killing the ammonia eating bacteria. No way it's that high if the fish are still alive.

Nitrite should be zero, but 0.3 isn't dangerous and is normal in a new tank that's 1/2 way through cycling.

Nitrate, lower the better, but once the tank starts to cycle it will increase. 10-20 is normal, if it gets up to 30 do some extra water changes.

pH - 7.5 is normal, don 't worry about that.

So, double check that Ammonia, if it is over 0.5, do an extra water change to keep the level down, then just keep monitoring and waiting, maybe with some extra water changes if needed. Same with the nitrite level.

Once the tank has ammonia=0, Nitrite=0 and Nitrate=5-30 then the tank is cycled and you can get some more fish. Some more tiger barbs would be the next addition.

Ian

It obviously isnt cycled. Look up the nitrogen cycle on google. Also, I hope your tank is atleast 30 gallons because that rainbow shark will get big. Lastly, I kind of doubt that your ammonia is at 8.0 because no fish can survive that