Your phone will need to be on the same network as your Hue bridge in order to update your evening and morning preferences.
You can change your evening lighting by tapping the gear icon in your Tonight card and scrolling to the Evening Lighting settings. You can adjust the brightness, the color temperature (if your bulbs allow), and how long before your bedtime the evening lighting will begin. When you select and change the brightness and color temperature dial, your lights will adjust in real time so you can preview your evening lighting.
For your morning lighting, the steps are similar to above, but you will change your morning lighting in the Tomorrow card. You will be able to set the brightness and color temperature that would feel comfortable in the morning. To help you wake gently and naturally, the lights will slowly turn on prior to your wake time. You select how long you would like the fade in to last.