When a person earns money, their age and dependency status has no bearing on the requirement for them to report that income. That income is considered self-employment income and she is required to report it, and pay taxes on it. Now if $1200 is all she made from all sources in the tax year, she will not pay "regular" taxes on it. But that does not negate the requirement to report the income to the IRS (and state, if your state taxes personal income.) For federal taxes (state is usually different) a tax return is required if a person earns more than $6300 (these numbers are for 2016 *ONLY*) of W-2 income, more than $1,050 of investment income, or more than $400 of self-employment income. At an absolute minimum, your daughter will be paying 15.3% self-employment tax on her art sales earnings. As far as the IRS is concerned, she earned that money while self-employed and "in business" for herself. Since it was more than $400 the tax return filing for 2016 is required by law.
She will need to file her own separate tax return for 2016. The SE tax that she will definitely pay, is basically the employer side of her social security and Medicare accounts. Since it's late, she will also pay late filing penalties, and interest on the unpaid SE tax liability.
Basically, she must file her own physically separate tax return. Included with that return with be a SCH C - Business Income & Expenses, which is where her sales income and associated business expenses will be reported.
Understand that a prior year return can not be filed with the online version of TurboTax. The online version is for the current tax year only. (presently, still for the 2017 tax year until Oct 2018). So she will need to purchase the CD/Desktop version of TurboTax. With the desktop version she will need "at least" TurboTax Deluxe 2016. Any version below that does not include the SCH C. If she will be claiming more than $100 in deductible business expenses, then she will need TurboTax Premier.
You can purchase TurboTax 2016 online directly from Intuit at https://turbotax.intuit.com/personal-taxes/past-years-products/ Make sure you are under the correct tab on that page before you purchase. Otherwise, if you purchase the product for the wrong tax year, you own it. Once you pay for it, you will be able to download the installation file immediately and install it on your computer.
If she is required to also file a state return, then the state is an add-on module that is purchased separately, from within the main federal program. If needed, the program will guide you through that purchase, download and installation process.
Finally, a prior year return can not be e-filed. The IRS says so. She will have to print it, sign it, and mail it to the IRS (and her state also, if applicable.)
Once the tax return is completed and mailed, do two things.
1) Save a copy of your return from within the TurboTax program in PDF format.
2) Print a copy of your saved PDF and keep it "FOREVER". As technology evolves, should you need that tax return in the future, it's very likely that the only way you will be able to see it, is with the paper copy you printed, or the PDF copy you saved on an external storage device such as a CD you burned it to.