You either earn tokens as rewards for activities that contribute and build the community, or you can buy tokens on the Uniswap decentralised exchange at the WPOL/OPEX Pool.
Buy OPEX Operational Excellence Tokens here using WPOL (Wrapped Polygon tokens)
https://app.uniswap.org/explore/pools/polygon/0x2E8aE39814879eacb2b3C72648f28563b624aa19
You will need to have WPOL tokens in your wallet in order to swap them for OPEX tokens.
You can either buy WPOL Tokens with US$ on a centralised exchange such as Coinbase or Binanace or convert POL Tokens into WPOL Tokens.