Where do I go to declare a scholarship I won? It's from a third party organisation, not the university I go to.

If it is taxable, enter it in the Education section in Deductions and Credits.   IRS Topic 421

There is no place to enter that in the income section of online TurboTax*. So, you enter at Educational Expenses and Scholarships, under Deductions and credits (not the income section).

After answering no to having a 1098-T**, answer yes to qualifying for an exception (that gets you to the entry screens). You will have to go thru the whole education interview to get to the scholarship screen. At the scholarship screen, enter the amount of the grant. When asked if any was used for room and board, answer yes. Then enter the amount you want to be taxable (usually all of it), in the pop up box. R&B are not "qualified educational  expenses".  So, this is how you tell TT that it is taxable. Note the wording at that screen “or other expenses”. You didn’t have to literally use the scholarship for R&B.  This will put it on line 8r of Schedule 1 (this line is new for 2022-3).

**If you do have a 1098-T, one of the follow-up questions will be do you have any scholarships not shown on the 1098-T. Enter the additional scholarship/stipend there.  

*There is in the download editions.