I was trying so many times add to dmoz my webiste and they didnt added I dont know what Im doing wrong
Try reading the sticky. Did you mean you suggested the site multiple times, which is against the guidelines or did you not read those either before suggesting a site?
Assuming your site was not flagged for spam, you should be OK. Don't worry about it, and just don't try again. There is no way to tell if it was flagged or if your site was rejected for other reasons, so just move forward and never ever look back. An ODP listing is not the end all of links, promote your site by other methods, and someday your site my show up in the directory.
you can submit your site to different categories if you site is so big. Just submit your category to the right category on dmoz.com
You can certainly choose to ignore our Suggestion Guidelines which forbid that. In return, we can choose to decide that you are a spammer and treat your suggestions accordingly. Free will in action