Download the latest nymea image for the Raspberry Pi 3.
Inset the micro SD-Card into your Raspberry Pi 3 and power on the device. Booting might take a while.
As long as the Raspberry Pi does not have any network connection, so let's say you don't have any LAN cable plugged in, nymea starts a Bluetooth service that helps you to get your Pi connected with your Wi-Fi network.
Now that your Raspberry Pi is connected to your Wi-Fi you are able to connect to nymea. Take care that your nymea:app is in the same network as your Raspberry Pi!
That's it! You are ready to add your devices and create some magic for your environment!