The office is the screen where the commander will spend most of his time when he is not in the field with his troops. From there you can manage the logistics and administrative details of your unit. The office offers a variety of options to the commander. These details are also explained in the overview page.
The calendar in the top left shows you how many days you have left before the end of your tour. When your tour ends you will sit in front of the task force commander and he will sign you for another tour OR not depending on merit. You can view your merit score in the career panel (by clicking the dog tags). Clicking the calendar will skip a day. Sometimes, skipping a day can be a good option. It allows wounded soldiers to recover hit points and to drop their fatigue level. Note that skipping a day will also slightly reduce the morale of your troops. Rangers are hard chargers and if they are not in the boonies killing communists they tend to get sad.
The beige folder will take you to your roster, where you can manage your team and select who will participate in the next patrol. As a commander you must manage your troop in order to keep everyone happy and well rested.
Information about your profile including rank, exp, intel, merit and ribbons.
Missions will appear as markings on your map. Hovering over each marking gives a brief description of what you have to do. Different markings indicate the type of mission. You have one mission available to you per rank.
Click this to blast some Vietnam-era tunes over on the website.
The coffee cup links you to this wiki, but I bet you already knew that ;)
Memos will appear in your inbox from time to time. Memos are basically correspondence between you and another officer such as a fellow commander or one of your own men. Before going out on patrol you are required to complete the day's paperwork, which usually involves some careful decision making on your part. Decisions you make can affect your profile stats such as rank, merit, and intel as well as your soldier's stats such as their morale, fatigue, and skill points.