Float comes pre-packaged with the Envato Market plugin, which enables you to get automatic updates for your theme without having to manually upload files.
Make sure you have installed and actived this plugin before continuing.
Once activated, click the Envato Market tab in your admin panel.
Within the Settings tab, click generate a personal token and follow the steps to get your Envato API Personal Token. Once you've received your token, paste it into the Token field (highlighted above) and click Save Changes.
You should now be connected to your ThemeForest account where you will see Float listed within the Themes tab. Your theme will automatically display notices within the admin panel whenever an update is available.
When an update is available, navigate to the WordPress Updates page via Dashboard ➝ Updates, select Float in the list of updatable themes, and click the Update Themes button.
Alternatively, you can update your theme via the Envato Market plugin by navigating to Envato Market ➝ Themes and clicking the Update Available link on the Float thumbnail.