To provide liquidity, visit the "Liquidity Pool" management page.
Choose the liquidity provider from the dropdown menu (PlasmaSwap, SushiSwap, UniSwap).
Select the token pair and enter the amount of liquidity you want to provide to the pool. You will need the right balance of both tokens.
Sign the transaction to approve both token contracts.
When successful, you are supplying liquidity to the pool and will receive LP tokens on your wallet to represent your share of the pool