I hate to be a huge downer, but the good-paying (read: more than a few nickels) ghostwriting gigs are usually contract, and depending how legit the employer is and where they are located, you might be disqualified because of age—most jurisdictions would require you to be 18 for the contract to not be voidable later, and that's not a risk anyone hiring you would be willing to take, that you could come back and say "lel that's mine give me dollars".
If you want to get jobs ghostwriting on here then the first thing you should do is make sure every bit of your writing that people can see (from deviations to journals to your ID) look professional and has no errors. Put up different kinds of your work here so that people can see what styles you are capable of, since you might be asked to write anything and not necessarily what you find fun to write. Get active within the community and advertise yourself, too.
Those bits of advice apply to attempting to be paid for writing anywhere, really.
i have done some ghost writing for some musicians, but if i were to give you any advice i would say put more of your work up for critique get some more feedback and get a little more recognition for your own work at first. Ghostwriting is a thankless job because no one should know you are doing it.
As for the price to charge for your work when you do it...it varies when i first work with someone i usually charge them half what i would normally charge for the first work and let them know if they want more done what the charge will be.Given that is for lyrics not so much literature.
Rated based on what you feel your work is worth and start there. there is always room for negotiation.