Go to RIF On Chain dApp this is the url: https://dapp.rifonchain.com/
You will see a menu allowing you to select your preferred wallet.

Once in the dapp you can mint and redeem USDRIF and RIFPRO tokens. Minting tokens is like creating the tokens by yourself. In this process, you lock RIF to be able to issue the equivalent in RIF On Chain's tokens.
The difference between buy/sell and mint/redeem is that when you carry out a buy/sell operation, you do it with another subject, be it a person or an exchange, and you exchange a token for another that already exists. On the other hand, when you mint/redeem, you do it directly with the smart contract through the RIF on Chain app or a wallet integrating the protocol, and you are creating or destroying the token.
Other way to get RIF On Chain tokens is by swapping them for tokens in Rootstock or other networks. You can check how to do it reading Swap tokens.