To Promote a Bridge Officer (Boff), go to the window that shows you your officers. Pick which officer you want to Promote, then Go to skills and spend the skill points you have on that officer, then go to the Status tab right next to the skills tab. at the bottom is a button that says Career Options, click that then the button that says promote. a pop up window will open up click the button that says promote this officer. Repeat as needed to get the officer to where you want him/her.
Well you need to understand a few things first. You only have so many Commissioned Officers slots available. Those slots are on the left hand side of the crew window. You start off with just a few. You will gain up to 6 as a Silver account as your get promotions to higher ranks. And you can purchase more Commissioned Officer slots from the C-Store. A Commissioned Officer officially joins your crew. You can assign them to Bridge Stations on your ship and/or on away teams on ground missions.
You can also have up to 12 Bridge Officer Candidates. These Bridge Officer Candidates are the list on the right sides of the 'Stations' tab of the crew window. Candidates you can use to train a Commissioned in a rare Bridge Officer Ability which isn't trainable via other methods. Of or can commission a Bridge Officer Candidate into your crew if your have an available empty Commissioned Officer slots (left side of the window).
Now you can only promote Commissioned Bridge Officers up to the rank below your. As a Commander rank, you can only promote Bridge Officers up to Lieutenant Commander. To promote a Bridge Officer your have to have spent a certain amount of Bridge Officer skill points (called Expertise) on their ground and/or space abilities. Once you have done that you can promote a Bridge officer to the next rank and open up the next pair of abilities. You gain Bridge Officer experience points (skill points or Expertise) along side of your Skill Points.
I tried to be as clear as possible. I hope that you can understand my Englihs or this translate into Romanian well.