Tank filtering

Question
I am considering purchasing a 10 gallon tank for my betta (Siamese Fighting Fish).
I know next to nothing so I was wondering how to change the water.
Do I completely change the water at regular intervals?
Is a filter needed?
If so, what kind?

Answer
Hello,
I'm sorry for the slow response time. I'm participating in U23 whitewater slalom world championships so I've been distracted.
The 10 gallon tank would be a great idea if you haven't purchased on already. you can do minor water changes every two weeks and be perfect. by minor I mean 10%-20%. Honestly, you don't NEED to, but it will improve the quality of your fish keeping experience.

I would use a sponge filter for a betta, if you don't mind the appearance too much. They do a great job, oxygenate the water well, and don't have too much flow, which is the most common problem with the betta's long fins. I have yet to encounter a poor quality brand, and nearly everyone makes filters for a 10 gallon tank. Being that a beta is a small fish with a low bioload, you could even use a 5 gallon tank filter.