Input the amount you want to stake or click "Max" for everything in your wallet. Click "Stake", then approve the transaction!! If you are interacting with this contract for the 1st time, you will need to approve of your spending first, then deposit. There will be two transaction needed in this scenario.
Stake your LP to get $WEAVE as reward
Withdrawing LP
Make sure you are at Weave LP staking page, input the amount you want to withdraw then click "withdraw".
During first few days of launch event, only "withdraw all" function is available.