Protect your computer with a password. From the Apple menu: > Preferences > Security & Privacy set a password in "Change Password..." and mark the checkbox "Require password" immediately.
Download and open the instalation package. Follow the instalation steps.
Start Umwelt, from the Launchpad
When you run it for the first time, a popup asks if you want to run the settings wizard. Clik Yes. If you already clicked No, then select the Umwelt Icon on the menu bar and "Preferences"
On the preferences dialog click on the button with the label "Click to select". Be sure that you already sucssefully paired your watch to your Mac, on step 1.
Your watch name should appear on the sheet with the paired watches. Select it and click the "Select this watch" button.
Umwelt should be able to connect to your watch. If not, be sure that Bluetooth is enabled on the watch. If you have a Pebble you might need to disconnect your phone from the Pebble, on your phone Pebble app.
When your watch is successfully connected, adjust the distance threshold. Have your watch at a confortable distance from the computer and move the threshold to a position a little below the current levels.
Select the "Lock/Unlock" tab.
Click the button to set the password for unlocking your computer. Umwelt will not share your password with any other application or device. The password will be stored in the Keychain and used for unlocking your computer, only.
Type your password twice in the open sheet and click the "Store Password" button. IF you change your Mac password, be sure to change it in Umwelt, also.