Need help to implement multithreading in C#

I am making an app in which for some reason when I click on a button I have to initiate a new form and at the same time create a new document in the google docs.
I've successfully implemented the above but while the app is busy making creating a new doc at google docs for that time being the newly loaded form's UI freezes.
I read somewhere that this can be avoided if I use multi threading.
So now I wanna ask should I create two threads and in one of them I should place the code for creating new form and in the other one I should place the code to create a document in google doc.
Or I should just create on thread in which I should place the code to create new google doc and let the new form creating code be in the main process??
Also What would be the easiest way to implement threading in an already written code?? Pleaseprovide with some reference reading material if possible.

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