The first step you must take if you want to become a military firefighter is, of course, to join the military. Decide which branch of the military you want to join, as there are likely to be several in your country. A bit of research online will usually help you figure out which branch is right for you; you can also consider visiting with a military recruiter who can help you make this decision. Once you join, you will need to complete your basic training before you can become a military firefighter.
During basic training, you will learn all the basic skills you will need to become a soldier. The length of time you will spend in basic training will vary according to the branch of the military you have joined and your country's specific requirements for all soldiers. You will likely spend several months in this phase of your training. Once you finish basic training successfully, you can take the next step to become a military firefighter, which is to establish your desire to pursue this path. You can do this by talking with a commanding officer or filling out the appropriate paperwork that will put you on a path to become a military firefighter.
The next phase of your training will also last several months or even a year, though it is unusual for training to take that long. You will enter the firefighter's school offered by your branch of the military, where you will learn the basic skills necessary to become a military firefighter and practice these skills in live, controlled fires. Be prepared for the physical rigors of the job, as well as the physical danger. You may face injury or death as a military firefighter, and you should be prepared to risk your own life to save others. You will probably need to pass a physical examination in order to become a military firefighter.
Once you have completed your training, you will probably act as a probationary firefighter or apprentice. During this period of time, you are likely to work with a more experienced soldier who will essentially monitor your progress as a firefighter. At this point, you will be qualified to fight fires and complete all other duties involved with a firefighting unit, and you will answer to your immediate supervisors or officers regarding the role you will play on a firefighting team.