Dear Ratnakar,
You must have received letter from the ESIC Dept for Interest and Damages.
According to the instructions mentioned in the letter, the challan has to be paid in the said heading.
On the website, once you log in, go to the link Recovery/Defaulter Challan and NOT omitted Wages.
In the drop down menu, you will find the list of various challan heads, like C-18(i) for Interest , D-18 for damages etc..
Select the relevant challan head and generate the challan.
Incase, you donot understand the head, you can send me the softcopy of the letter and I'll guide you.