where do I add my spousal support

[DoninGA]

If your separation or divorce decree was signed after 12/31/2018, then alimony (spousal support) is not entered on a federal tax return.

Otherwise -

To enter Alimony payments received -

Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Less Common Income
On Alimony Received, click the start or update button

[MayaD]

For divorce agreements dated January 1, 2019, or after you don't have to include information about alimony payments on your federal income tax returns since it isn't considered income or a deduction

For more information check here.