Head over to https://arsnap.org where the latest version of the wallet is deployed and click on "Connect with Metamask".
The best way to get started with Arsnap right now is to use accessible at https://arsnap.org. It will allow you to manage Arweave keys, monitor what dApps are connected to the Snaps and manage their permissions.
The Snap allows you to manage Arweave keys derivated from your Metamask account and sign bytes with them.
The Snap does not allow to recover wallets that are not derived from your Metamask account. Be sure to have these backed up somewhere if you are going to import them inside Arsnap.
The fastest way to get help is by joining the official Arweave discord
server and ask your questions in the #arsnap-metamask channel.