It's a little complicated, but begin with line 16 and then look at lines 17-23. They will have some additional taxes, but also some credits, where the net effect with line 16 is line 24. You will need to understand if any of the amounts in lines 17-23 will continue for the year you claim the credit to determin what your total tax will be.
It's difficult to find a definitive answer as to how long the credit can be carried forward, even on the IRS website. I've seen next year, 5 years, 10 years, as long as the credit is still available, etc. The credit is available for the next 10 years, so I think you will be safe.
