Where do I enter my 1099-D?

There is no such Form 1099-D.  Did you mean a Form 1099-DIV?

You added a link to social security.  What kind of 1099 did you get?  Is it for Social Security or SS Disability?  Those are on a SSA-1099.

Enter a SSA-1099, SSA-1099-SM or RRB-1099 under

Federal Taxes on the left side or top

Wages and Income

Then scroll down to Retirement Plans and Social Security

Then the second line - Social Security (SSA-1099. RRB-1099) - click the Start or Revisit button