I have a 1099-G separate from my main 1099-g. It has a Refund in Box 2 and 3, but in TurboTax there is only Box 1 or 4, do I need to input this figure?

Yes that is for a state refund you got last year.  It has its own spot to enter it.

To enter a state refund just type  1099-G (with the dash)  in the search box at the top of your return and click on Jump To it.

OR  Enter the 1099G under

 Federal on left

Wages & Income at top

 Scroll down to 1099-Misc and  Other Common Income

      You might need click on Show More to expand the section

Then it's the first line for Refunds Received for State/Local Tax Returns - Click Start

     You do not want the next line that says Other 1099G Income

On the first screen check YES - Received a State Refund.

A State Tax Refund is taxable if you itemized deductions on that prior year's federal return and took a deduction for state income taxes instead of the sale tax.  You got a deduction benefit for it so now you have to include it as income. If you took the standard deduction it is not taxable and you don't need to report it.