You don't have to do anything special to get it. It is automatic. Just enter the full amount on your 1099G. Your unemployment compensation will be on Schedule 1 line 7. The exclusion will be on Schedule 1 Line 8 as a negative number. The result flows to Form 1040 Line 8.
If the exclusion doesn't show up and reduce your income then delete the 1099G and re enter it.