The instructions are different for Online and Desktop, plus I don't work on a Mac, but this is how the 1099-MISC for an AmeriCorps award is entered in Windows.
Be sure to Delete the first entry.
In the desktop
program, start or open your return
Click FEDERAL
TAXES
Click Wages
& Income
Click "I'll
choose what to work on" if needed
Scroll down to Miscellaneous
Income, 1099-A, 1099-C (the last option) under "Less
Common Income" and click Start
Scroll down to the
last option "Other reportable income" and
click Start
Answer "Yes" and Continue
Type AmeriCorps 1099-MISC into
the description box and the amount.