To become a general in Bitlife, you will need to work hard, but more importantly, you will need to join the military as an officer. If you want to join the army as an officer, it can be done by clicking on the army tab and choosing the join the army as an officer option.
If accepted you will eventually work up the ranks to become a general in your nation's military. However, becoming a general will still require some extra steps; luckily, we have all of them explained below.
The first step and most important one is to join the military as an officer. To do it, you will need to graduate secondary school and obtain a degree in college - it doesn't matter what degree.
That said, we recommend creating a character with decent smarts and athletic stats to accomplish this goal. Go to both the gym and public library while also reading books to keep your stats high, as well.
You will need to keep doing this until you graduate both from high school and university. Once you graduate from both, you will then be able to find the option to join the army as an officer via the military tab under careers.
After you join the ranks as an officer, all you will need to do is to use the work hard option under jobs and complete deployments. Deployments are basically minesweeper mini-games, and you will need to complete them to both survive in the military and get promoted. If these deployments give you trouble, we have a handy guide that will be linked above to help you out.