http://xi2nhkuzm2hzgyedprs3n65wmudrq4rekbzire67oomiwk5x5h6w7nqd.onion/tr/get-started/faq
In past, you needed Bitcoin to buy Monero, but that's not the case anymore. You can directly trade Monero for national currencies (USD, EUR, GBP, etc) or other cryptocurrencies on many exchanges. Some require KYC (proof of identification); others do not, like decentralized exchanges.