How do I add a college to my tax return form 1098-T

You can edit your tuition amounts or add a school only from the Education Summary Page by editing the school information or clicking the Add New School button ; follow these steps:

When you are signed into your tax return, you can type 1098-t into the search bar at the top of the screen, hit enter, then click on the Jump to 1098-t link to get back to the education section in TurboTax.   You will be taken to the education section but the exact screen you will land on depends on where you left off.  Click through the screens until you get to the Expenses Summary, which will list all students on your return.  From here you can add another student.

In order to change the tuition amounts or add another school, you will need to click on Edit, next to the name of the student on the screen titled Your Education Expenses Summary.  

That will take you to a screen titled Here's Your Education Summary.  From this screen, you can edit the tuition amounts by clicking on Edit next to the name of the school.   Or you can add another school by clicking on Add New School.