How to give an officer to another player?

You cant give your officers to another player. There is simply no way in the game to do this. However, if what you were referring to is to send out help when your corps members are asking of UP Officers in the counterattack, you'll simply have to go to "Corps" tab, pick "Corps Help" on the Corps Bonus Section, and then the "Assist" tab, and then pick which officers you'll send for help. Take note that this option will only be available when a corp member asks you for help.