You can file Form W-7, Application for IRS Individual Taxpayer Identification Number (ITIN), with your federal income tax return. You must also include original documentation or certified copies from the issuing agency to prove identity and foreign status.
IRS Form W-7 - https://www.irs.gov/forms-pubs/about-form-w-7
The Form W-7 has to be included with the tax return so you will have to print and mail the return.
See this TurboTax support FAQ for how to print and mail a return using the online editions - https://ttlc.intuit.com/turbotax-support/en-us/help-article/printers-printing/print-mail-return-turb...
