how can i add the reference to a third party library when the web application is already in the webserver

I am working on a web application built with vb.net and asp.net. the web application is already stored in the web server. I am creating some new features in the web app.

If have to incude new third party library (e.g; itextsharp etc) in the project how can i add reference to the dll files in the web server?

in the webserver there is visual studio editor to edit the webapp. When there is a change in file we just update the file by replacing with new file.

will it work if I just copy the dll files in bin folder (in the web server)

please suggest how to deal woth it.

i am a new learner in vb.net and asp.net . So please forgive if my question sounds stupid. but please advice with right suggestion.