YoVille will NEVER ask for your password, so please be wary of malicious emails and/or forum posts that request your password, including via web links.
Try hovering your mouse above the "URL" button here. It says: [url=http://]URL text[/url]
It means you should put the url (link) after the equal sign (specifically after the "url=") then put the text you want to be the text link between the url tabs (delete the "URL text" then replace with the text.