How to improve the command of the true three kingdoms and seven generals

Refer to the method of increasing command in the biography of the true Three Kingdoms Warriors 7 Heroes.

Reference question:

How to add commands? Main mode. Command is always zero. I found many posts, probably named as Lieutenant Skills, but how did the Lieutenant start the skills? I've studied it for a long time and I haven't figured it out. Please let me know!

Reference method:

Press F 1 in the battlefield, and then select command guard to use skills. When they are finished, they will give you some experience. When you have accumulated enough experience, your command will be upgraded to the highest level of 99, and you can take three unparalleled commanders.

Generally speaking, if you want to increase your command, your friends should instruct the guards to use their skills first.