The MWO non-battlefield interface has standard top and bottom menus.
Home - Takes you to the landing screen. See Mech Bay for more information.
MechLab - See the loadout of your current 'Mech. See Mech Lab for more information.
Store - Stock your 'Mech stable. See Store for more information.
Comp Play - Takes you to seasonal competitive play.
Faction Play - Fight for the Inner Sphere. See Faction Play for more information.
Solaris - Duel for your Patrons. See Solaris for more information.
Quick Play - Launch into 12v12 battle by yourself or with a group.
Hover over the Quick Play button to see game status information. Matchmaker Status shows you the percentage of 'Mech classes playing at that time. Below are the ping for each of the servers: North American, European and Oceanic. The above image was taken from the western coast of North America.
The small drop menu to the left of the Quick Play button tells MM which servers you are looking to play on. Only selecting the server you are closest too may reduce your in-game latency, but may increase your wait time as MM creates matches.