Use F1 to F12 to open these windows as shortcut. Here are the following guides:

Instructions - Shows you keys from F1 to F12
Equip - Like Shortcut Window you can equip weapons, armor, mags and shields (units too)
Technique - Use Techniques
Mag Feed - Feed Mags (Mags will evolve in a certain levels)
Guild Card - Trade or Search Player's Guild Cards (Example Friend Requests)
Send Mail - Send mail to players (Search all players first then send mail)
Symbol Chat - Use Symbol Chats (Used for Communications)
Team - Displays Team Members
Team Log Window - Shows Team Log (Dunno much about it)
Normal/Team Chat - Chat with teams
Keyboard Control - Switches to play mode or chat mode (I don't remember)
Main Menu - The General