From the control panel, click Create in the upper-right, then click Cloud Firewalls.
Choose a name and customize any inbound and outbound rules. There are 4 pre-configured rules suggested by default.
Choose the Droplets you want to apply the firewall to. You can also select Droplets by tag, which allows you to apply firewalls rules to a Droplet at creation time and simplifies managing your Droplets in bulk.
Click Create Firewall.
From the control panel, click Networking, then click Firewalls and choose the firewall you want to modify.
From the Rules tab, you can customize its inbound and outbound rules. Use the More menu on an existing rule to Edit Rule or Delete Rule.
From the Droplets tab, you can customize which Droplets are protected by this firewall. Use the More menu on an existing Droplet on this page to Remove it from the Firewall.