How to Invest in a Roth IRA for a Teenager

H.C. in Connecticut says his 13-year-old daughter has earned a few hundred dollars from sales of her paintings at a local gallery show. Do these art commissions count as income that she can invest into a Roth? And if so, where would you recommend I open the account for her with this small sum as a start? Fidelity instead of Vanguard or Schwab,. Fidelity has such an emphasis on offering investment accounts for teenagers. Is it the freedom, the Fidelity Freedom? That's it.