You shouldn't need to be registered to submit a weblink to a site however you must be staff to physically add the link by validating it. I'm unsure if there's a way to allow visitors to manually add their links but believe me, it's something you don't want your visitors to do as it can be easily exploited.

Allow just anyone to post links on your site and you are risking becoming a link farm and penalized by popular search engines such as google, not to mention your risking allowing tards to post links to any site they wish such as tobacco, pr0n, hate, racism, etc.

Believe me, it can happen to you!