Just finished my return but In checking I don’t see a 1120-s form for my s Corp. can I still add that?

Did you get a K-1 from the 1120 S business return?  You know you have to prepare the 1120 return separately first?

To enter a K-1 go to

Federal Taxes Tab or Personal (Home & Business version)

Wages and Income

Then scroll way down to Business items

Schedules K-1, Q - Click the Start or Update button

Be sure to pick the right kind of K-1. There are 3 kinds, 1041, 1065 & 1120S

Enter each k-1 separately.

Do you need to prepare and file the 1120 S return?  You need Turbo Tax Business.

The small business program (TT Business) is for 1120 Corporation, 1120S Corp, 1065 Partnership or 1041 Estate/Trust returns and will not do your personal 1040 return.   It  is a separate program from the Desktop Home & Business program or the Online Self Employed version.

Turbo Tax Business  is not available to do online or on a Mac.  You can buy the Window's version here.  And you can have both TT Business and TT Home & Business (or any personal version) installed on  your computer at the same time.

https://turbotax.intuit.com/small-business-taxes

Desktop Windows System Requirements

https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-windows-software/00/26175