Select which token pair you want to add liquidity for
Fill in the amounts you want to add to the liquidity pool.
It may ask you to Approve the tokens - you will have to send these "approve transactions" first.
Once you've approved the token you can hit Supply
The transaction will provide you with some UNI-V2 LP tokens in your wallet. These are Uniswap LP tokens and represent the share you've deposited in the pool. All pools are labeled as UNI-V2 LP but represent different pools.