Hi aravindbalu,
Launch provides extension for Double Click Floodlight tag and it requires no custom code. Follow the steps to place floodlight tag on your site.
1) Search for Double Click Floodlight in extension tab of launch and install it.
2) Now you have to create new Rule in the Rule tab of launch and use the installed extension. Provide the Event and condition which will ensure when the Floodlight to fire and in the action section select the installed extension later add the details provided by marketing team in configuration i.e (src,type.cat,ord etc).
3) Build the library with the changes done in step 1 and 2 and you would be able to see Double Click Flood light firing.
Hope this Helps .........
Thanks,
Shweta Bakshi