Ex-soldier here too
To answer your question how is a piece of string! There's no answer.
Think of this as your recruit training, you'll basically work long and
hard and get sod all in return... your gona make 100s of mistakes.
Don't rely on here for any income at all, get work somewhere else and
treat this place as an online education that will slowly start paying you
money back.
You'll need things like domains and hosting to begin with. Take a look at godaddy
to give you an idea of prices. After that then read, read, read!
You've one thing going for you that 99% of this forum doesn't that's the work ethic
of a donkey... I've spent countless amounts of days doing "24 hour exercises" working solid, even keeping going to about 36 hours before I need sleep.
Work like a dog, learn from your mistakes, and expect to go bust at some point. Once all these realities are all in your head, any sort of failure is alot easier to take. A mate once told me 0.2% of online marketers ever succeed, so keep that reality in your head, and work hard!
Once you can make $1 a day you then start to go for $10. $100 a day is very easy for me now... at one stage $25 a day was just a very distant dream. It's all about making a method that makes you $70 a day, then another $20, then another $50... then you scale up those efforts with software and outsourcing.
One last piece of advice, don't buy any software unless it will make you money within the week and you know exactly what you need it for, understand it inside and out before paying a penny... and be careful of scammers, there's countless amounts of people who will try and fleece you with empty promises.