In order to create a liquidity pair, click the ‘Liquidity’ button in the top navigation, select two tokens, and proceed to the following window. Click on "Add Liquidity" which will allow you to fix the initial price (if a new pair), set the amount, and continue.
If you have not previously approved adding liquidity to the pair, you will be required to approve spending of those tokens. By approving, it allows the smart contracts to take those tokens from your wallet and put them inside the liquidity pool. Click the 'Approve' button to have the approval transaction populate in your wallet. If you have previously approved a LP for this pair, you can continue with the 'Add +' button.
Once you click 'Add +', you will need to confirm that transaction in your wallet.
Once confirmed in your wallet, you will receive two notifications about your transaction from OpenSwap: a notification the transaction was sent and a notification the transaction was completed.
Now that you have liquidity, you can continue to the Staking section to learn how to earn oSwap tokens.