You'll need to authenticate your requests to imgur via oauth2. The account that is used to authenticate will be the account that does the uploads.
A full description of oauth is a bit beyond the scope of this answer, but in short, you're using the right http library in requests
because it is often simpler than other approaches.
I like requests-oauthlib library which is recommended by requests. It works well with twitter's api too.
I should also note that imgur has a sample python app called imgur-python. Check out main.py for a bit more of a lead on things.