Your fish's water will be murky for anywhere from 2 days to a couple of weeks. That's normal and will correct itself.
Reading literature on Beta can make pet ownership seem daunting. But honestly, Betas are relatively hardy and easy to care for. The two biggest worries are feeding (4-6 little food pellets twice a day, more than that and you will kill your fish and make his water dirtier more quickly) and keeping your fish warm during colder months. If you can manage those things, then your pet should live 2-3 years.
Cleaning is really a secondary worry. You should aim for every month... However, if you get too busy, your fish won't go belly up if you drag it out to around 2 or 2 1/2 months, like we did. Oops.
2 or so cups of water. I use filtered. If you use distilled water you don't HAVE to condition your water, so that is probably best.
Step 3: Empty Measuring Cup
For getting some of the dingy water out of the tank.
* I use two separate cups because it makes it quicker for me, but you only need one
Step 4: Brand New Tooth Brush
Why brand new? Fish are sensitive even the slightest people germs you introduce to your fish's tank, or toothpaste residue could potentially wreak havok with your pets environment.
Besides, I get free tooth brushes from the dentist and I don't particularly care for them, so they're perfect.
Remember, if your going to keep this tooth brush for future tank cleanings, don't use it for anything else.
Step 5: Beta Water Conditioner
A must for tap water. Optional for distilled water. I recommend it even for distilled because the conditioner encourages protective slime growth on your fish.
Step 6: Bucket Or Tub For Dirty Water
Kinda speaks for itself. This isn't necessary if you're cleaning near a sink, unless you like to add this water to your plants... They will love it. It's full if fish poo and slime and fish food particles.