Have a question about how the TVTropes wiki works? No one knows this community better than the people in it, so ask away! Ask the Tropers is the page you come to when you have a question burning in your brain and the support pages didn't help.
It's not for everything, though. For a list of all the resources for your questions, click here. You can also go to this Directory thread
for ongoing cleanup projects.
If you mean for your own fanfiction, then yes, that's fine; go to How to Create a Work Page for details. Just remember a few things: the page needs a non-stubby description and examples of at least three distinct tropes, all with proper explanation (no Zero Context Examples), all of which should be cross-wicked to the appropriate trope pages. The page itself should also be put on at least one suitable index.
Remember also that The Fic May Be Yours, but the Trope Page Is Ours; you don't have final say on what can or cannot go on the page just because you're the author of the work. Along similar lines, don't write the page in the first person voice. And don't add audience reaction (i.e., YMMV) tropes for your own work; the audience decides how it reacts to a work, not the creator of the work. Similarly, don't add Word of God entries or any Trivia items that are not independently verifiable.
As long as you keep that in mind, have at it!
What mlsmithca said basically, but do we need to cite The Fic May Be Yours, but the Trope Page Is Ours whenever someone asks about creating a page for their work? It's somewhat presumptuous and the vast majority of people don't remove their work pages.
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
I was wondering if it was possible to make a trope page for a fanfiction? How do I do it?