I hear the coronavirus checks for $1200 will be sent to the direct deposit acct on file with the IRS. I had to pay taxes so I don't have this on file. How can I add it?

Since you owed taxes on your tax return, there is no way to add direct deposit information on your tax return. In this case, the check will probably be mailed to the address listed on your return. 

are you on social security?  the IRS will use the bank information on file with Social Security as well.