You need about 20 posts to post links. As much as you may hate it, it's to prevent bots or spammers from spamming their links here.
About your second issue - the person or website you are trying to credit is most likely censored by the filter. So... You should just write their usernames instead.
About your third issue - go on a site like tinypic, upload the file, and then take the forum url and then copy + paste it to your thread.