We want to know what paperwork and licenses we need to start our business. Who do we pay our taxes to? and How old do you have to be to start a business?
The licenses you must obtain will depend on what city you open your business in. Check on the city's website to see if a business license or any additional permit is required. If you want to file a corporation, you will do that with the secretary of state. If you don't do a corporation, you will need a Fictitious Business Name, which is filed with your county. Taxes get paid to the Franchise Tax Board and to the IRS. Be careful, it might be best to consult an attorney to make sure that everything is done right in the beginning, it is often cheaper than having to pay fines for late or incorrect filings.
Creating a business isn't a "one size fits all" type of thing, so before you even think about starting a business, you need to do some reading about what's involved. A single general question about licenses and taxes on a public forum like this one isn't a substitute for getting real, individualized legal and accounting advice, and your question indicates that you're starting from scratch and you're very young. Minors' contract are subject to special rules, so you need to be particularly careful if you're not 18 yet.
Start with one of more of the "how to" guides linked below, then see a lawyer.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.