Urgent : updation of dsc for online tds return

Dear All..

I had registered my dsc on tin-nsdl site andf used to e file my returns on tin nsdl, but nw my dsc has expired and i have obtained new dsc.. but now I dont know how to update my dsc, so that i can efile my tds returns.. 

Also, i have a doubt whether i have to register the dsc on traces or first update it on tin nsdl and then traces? I already have a traces login id..

Please let me know if I have to pay some fees for updating dsc and the procedure to update dsc for online tds returns

Please help 

Thanking You