module issues: carrier

[sandyko]

I am new to prestashop like just one day.

 

I have installed mycarrier module which is supposed to get its data from webservices. Going through prestashop I found that in fourth step of shipping carrier are listed using template order-carrier.tpl . Now I want to add if user select mycarrer as option then it should load drop down of options. I dont have probelm in implementing those functionality as I am experienced PHP developer, I am just having difficulty where(in mycarrier module or carrier module?) to calculate those webservices data so that i can pass it to tpl file and another confustion where tpl file should be am I supposed to override order-carrier.tpl file or I shall create another tpl file. Or do i need to create tpl file form my module mycarrier or what?

 

Looking forward for guidence.