first start an amended return by using that link
for schedule C or E (rental) go to that business section
if for example you listed insurance as $20K but it should be $25K just change it to $25K.
also make sure that any previous payment or refund is entered. Turbotax may have left them blank.
you don't amend until the original is fully processed
if this a k-1 change, you first need to file an amended return for the partnership or S-Corp. then you would follow a similar procedure as above by changing the amounts on the lines to reflect the revised k-1