Where does "Dividends in arrears" fall in account classifications. I know its common stock but would it fall under, the contributed capital of common stock, the retained earnings of common stock or other stock holders equity

There is no account for Dividends in arrears. That would just be a note to the financial statement and would require you pay those out (typically to preferred shareholders) before you pay dividends to common shareholders.

So while there may be Dividends in arrears, you will not have any specific account set up, just a not to the financial statement.

And when you pay them, they are just like paying normal dividends, in terms of their treatment once you pay them.