Click +Add Contact and add all the contact addresses that you want to include in the multisig wallet.
For example; Bob, Charlie and Dave.
Step 2
Go to Accounts -> +Multisig
From the available signatories, select the ones that you want to include in the multisig.
Add a threshold. A threshold of 2 means a minimum of 2 signatories are required to sign the transactions.
Give the multisig wallet a name.
Click "Create".
Step 3
The multisig wallet is created.
To test the multisig wallet, it is recommended to first use Shibuya testnet. You can get SBY faucet from https://portal.astar.networ by connecting your own wallet.
After getting the SBY faucet, send the SBY tokens to the multisig wallet and then you can start playing around.