I have a student who was late for 1st hour, checked in; and is now absent from my class. The correction for the a.m. class was rectified. How do I now mark this student absent in my 7th hour class?

When there is already an attendance code in the Out field and you need to enter an additional one for a Tardy or a Skipped, you should click in the Out field and choose Post New Tardy-To-Class if the student is Tardy or choose Post New/Multiple Checkout(s) if the student is Skipping.