To create a multisig transaction you can follow these steps:

1. On the multisig page, click on "New Transaction".

2. Select the transaction type. "Standard" transactions are used to spend ADA or any asset from the multisig.This will be the most common type of transaction that you will use. "Staking" transactions are used to stake the multisig's ADA to a stakepool. "Register" transactions can be used to register the stake credential in order to stake. This registering step is only necessary for new wallets that have never been staked and it will be automatically executed when creating a "Staking" transaction if the wallet hasn't been staked previously, so you will rarely need to use this type of transaction. "Withdraw rewards" transactions can be used to withdraw staking rewards accumulated by the wallet.

3. Fill the required values for the transaction. If it is a staking transaction you will only be required to specify a Stakepool ID (starting with 'pool...') For a "Standard" transacton you will need to specify the receivers and the assets being sent to them. You can also optionally add a message that will be included on the transaction metadata.

4. Finally, click on "Create & Save" to create the transaction. You will be redirected to the transaction page.