Firstly, it is great to see that you are passionate to learn something new and join the job market. As you are a US citizen, you have many options. Before you start training, I suggest you look at the typical jobs in federal job portal to see the job requirements. The reason I say that is, if you do the course and the jobs require you to have experience, then you are in trouble. So, doing some homework and picking up the jobs that are like entry level with minimum computer knowledge would be ideal to start your career. Once you are comfortable, in year or so, you can pick up a little advanced topics and build your professional career in IT.
Regarding pay, it all depends on the location and job expectations. As you are starting your career from Ground up, you can expect anywhere from 40K to 70K per year, depending on the state and place. You can check on Salary.com for average wages.
Joing a good school for 1 year program or so, will get you access to many resources that school offers. I think, it is a great idea to pick up a course at a school or at least a community college.