Hi Esperanza,
Here is the User Guide to help you post on the forum:
http://www.nuestrosranchos.org/userguide
If you just want to make a quick post or upload a document, you can just sign in and on the right below your user name click "Post a forum topic," then just choose a Subject, a Forum and write your post. Below that is a section to upload a document towards the bottom called "File attachments."
Christopher de Cuellar