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"
And then "Confirm Supply"
🧙♂️ Note: You always need the same amount of token worth on both sides, e.g $100 in YFBTC and $100 in ETH.
Then a transaction will pop-up for you to sign in your wallet (like MetaMask) - after the transaction is complete you will have successfully added liquidity.
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.