Call external library from asp.net web form

Question

I need to call a function which sets off a bunch of long running database operations from an asp web page. My function is in an external class library. I simply need the page to call the function and move on, ie. not wait for a response. Do I create an async call from the asp page? If so how? Or am I going about this the wrong way and should create the db operations within the asp site and use as an async method there? Haven't done this before (obviously!). Any direction much appreciated!