Dear Razi,
Both Form-5&6 requires to send to ESI authority with CA certification on form-5.
Form-5 is the summary of paid challans for six months, and Form-6 is the details of employee contribution during the six months ex. (total working days, total wage & total contribution paid against the employee).
Furthermore is given in both the forms and easily available to download from CiteHR.
-Sandeep.