I filed for one job, got my taxes, but did not file for a previous job I had on the same year. How do I go about filing for the second job?

[DoninGA]

All income from all sources is entered on only One tax return.  You will have to amend the tax return that you filed to add the income from the other job.

See this TurboTax support FAQ for amending a current year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-curr...

[ThomasM125]

You will have to prepare an amended return to report your additional income and tax withheld. If your taxes increase less than the amount of your tax withheld, you will get a refund of the difference, otherwise you may owe additional taxes. You should wait until your tax return that you submitted is processed and you have your refund if applicable before you submit your amended return. You will see an option for the amended return when you log into your TurboTax program.