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.