Tezos, Tez, or XTZ is the native Tezos blockchain coin that is used not only to purchase other assets but to pay all the fees within the Tezos network. You will need some Tez to start trading on QuipuSwap.
To buy Tez with fiat you can use any external exchange. Acquire XTZ and send them to your Tezos wallet.
Centralized exchanges require KYC but they are still the most reliable venue to buy crypto with fiat. Check this page for a list of exchanges that support Tezos. Pick an exchange, register an account, buy Tezos and send these tokens to your Tezos address.