1: The Lotus will contact you periodically throughout your mission. Listen to her; it could save your life!
2: The Minimap will help you navigate the locales your missions take place in. Follow the red objective symbol- it will lead you to your mission objective. Teammates will appear as a blue lotus symbol on the map. Remember, sticking together will give you the best experience!
3: Your Warframe Readout will display the vital information needed to stay alive. Your Shields, displayed as the large blue number, will regenerate over time. Once your shields are gone, you'll lose health, which is shown as the large red number. The current rank of the Warframe is indicated by the number next to the Warframe name. The current level of experience is represented by the white bar, the bar is filled the closer the Warframe is to being ranked up.
4: The Weapon Readout shows the important information about your equipped weapon. Like the Warframe Readout, the current rank of the weapon is indicated by the number next to the weapon name. The current level of experience is represented by the white bar, the bar is filled the closer the weapon is to being ranked up. Watch the maximum ammo count on the right and replenish it with various pickups you'll find during the mission.
5: Your Warframe's Abilities will be displayed here. The currently selected ability will be highlighted blue. Other abilities will be white, or grey if you lack the energy to activate them.
6: Use the Chat Box to communicate with the other players in the mission and to keep track of who has connected or disconnected.
7: If your targeting reticule is pointed at an enemy, you can see their Health and Description. If an enemy's health is blue, they possess a regenerating shield like your Warframe!
8: Challenges will appear during your missions. If you manage to complete the challenge, you will earn bonus affinity for your Warframe!
9: Credits, Foundry materials, Mods and Affinity drops picked up during a Mission are displayed here.
10: Occasionally you may find Mods in your missions that you can use to upgrade your Warframe and Weapons. When you pick one up, it will appear here, with a description of its effects.