There are different ways to get tokens, both buying and minting them.
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 (such as the TEX) 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 Money on Chain app or a wallet like Defiant, and you are creating or destroying the token.
Receiving tokens from a third party
As soon as you finished setting up your wallet you can receive Money On Chain's tokens from any user. The only thing you need to do is to share your public key with the other party.
Remember that you should never share your private key or your seed words.
Minting tokens is like creating the tokens by yourself. In this process you lock rBTC to be able to issue the equivalent in Money On Chain's tokens.
Buying on a secondary market
You can also get tokens in a secondary market (like the TEX) or a swap app (like RSKSwap).