How to upload media files via API to Campaign manager 360

Hello, I am using the google.dfareporting library to connect my application to Campaign manager 360, and in the creativeAssets.insert method, I can upload the metadata of a media file.
My question is, is there any other method to upload media files in this library?

Or is it that the only way to do it is by making a post to the following url?
https://dfareporting.googleapis.com/upload/dfareporting/v3.5/userprofiles/{profileId}/creativeAssets/{advertiserId}/creativeAssets

Could you show me an example to upload media files to Campaign manager 360 from the API?
I've been after this for a long time and I can't solve it.

Thank you very much!