Thank you for getting back to us with the additional information.
The articles that Ivan has linked do not pertain only to developing modules. These are help articles that explain the use of the Libraries module API. Having this said, I can add that you will need to use the Telerik.Libraries, and probably Telerik.Libraries.Data assemblies in order to use the Library Manager. In your code you should create an instance of this manger, to be able to work with Sitefinity libraries, since you would most probably want to upload the files in an existing library.
Once you have uploaded the file (.pdf) for example, you might wish to create a page, or use an existing one, within your website that will display the newly added file. For this you would need to use the Pages API
, we also have a webinar, explaining how to use Sitefinity's API. You can take a look at the Sitefinity API tips & tricks
Currently we do not have any help articles prepared on how to use the Sitefinity classes outside of the context of your website. However this basically should not be a problem, as you just need to reference the needed assemblies (you might already know that). You would also need to provide the appropriate connection strings in order for the content providers that you are using to know where the data should be stored.
Please, keep us posted on how your implementation is going.
the Telerik team