What should I do with the IT3(a) and IT3(b) I received?

I received it3a and b from GEPF what can I do with it?

The IT3a should have been submitted to SARS already, so you will see it on your tax return when you are ready to submit it and the IT3b amounts you need you complete on your tax return under the section called local investment income.
You can Register for TaxTim and maybe we can help you submit your tax return.