Quick answer.
When you by weapon systems they require officers and soldiers. Officers are mid level mangers, soldiers low level workers. make sure to check ed priorities you can adjust them if needed. Remember if your short (either) the officers / soldiers they will be pulled from your factories. Try to avoid this. large armies kill economies. If possible invest in your infrastructure first, High level of education critical to success build strong health care as well as transportation build your factories produce a positive cash flow. I'm sure others will have good advice for you both. Good luck have fun.
Rob