As far as your report, use standard web quoting method, dont need hillbilly1972 said on imdb

I lack some information to fully quote this source, as it is the Author of this entry ,etc.
Right, and that's kind of by design. IMDb owns our contributions; depending upon the type of contribution, that is. In certain ways, IMDb is like an encyclopedia or other reference works. You're probably not even supposed to be citing reference materials for your supposed research paper, but that depends upon what your audience requires.
Where can I find this information?
You won't be able to find the information. Sorry.

Depends on which citation style you are using.
Here is an example how to cite a website with or without an author according to MLA:
http://www.easybib.com/guides/citation-guides/mla-format/how-to-cite-a-website-mla/
In general, if an author cannot be located, you can leave this information out of the citation.