HOW TO INVEST IN ROTH IRA

Hello,

I am 20 years old I am a part time college student, full time employee for a very profitable agricultural company. I have worked full time since graduating high school while attending school part time in the evenings. I have a reserve fund for emergency purposes and have the desire to begin to invest in a Roth IRA. My company currently does not provide a 401k until I graduate with my degree(a year from now), and am a salaries do employee. I currently make anywhere from 45k to 55k a year, live with parents, only bill is a car payment I would really like to invest this money instead of spending it on other materialistic things that will only depreciate in times. And before i am told to invest in myself I'd like to let you know I have a gym pass, I try to life as healthy of a lifestyle as I can, I have plenty of nice interview clothes, i don't plan on investing all my money and not having enough to enjoy myself at this age, just what is extra. I have a question on what funds to invest in through fidelity. FUSEX v.s. FDEWX ??

Can I invest in two or more funds at the same time and is that recommended?

Thank you