Hi i want create in my FTP folder named forum and uplaod Xenforo inside it, this folder named xenforo its default on 775 it is ok or i must give 777 permission?
The only place XenForo needs write permissions are in the data/ and internal_data/ directories. Really, if you can avoid it, you don't want the web server to be able to write to the rest of the XenForo files. However, the specific settings might vary based on your host. 755 (or 644 on the files) would likely be fine outside of those directories.