You'll have to check your forms.
The amount in box 1b is included in 1a....so only the 1a value is used. The 1b value is the sub-amount of 1a that is eligible for special tax treatment in the tax calculations.
The 2a value should be part of your tax return and will add to your AGI, but it may not incur extra taxes (at the moment)...depending on it's value and on what other income you've entered into your tax file at this point .. The 2a value would add into line 6 on your form 1040, so it does add into your AGI.
(Depending on what else you enter in your tax return about your investment income, a Schedule D may also be included, and those 2a $$ would show up on line 13 of the Sched D...but a sched D is not always required....TTX will include it if it's needed).