To use a signature and complete it with personal text, you must at least rank up to Junior Member.
It does not complete anything. You can use a signature and personal text when your account is at Junior member rank or you can decide to use none of them, or only one of them like signature without personal text or personal text without signature. It's personal choice.
I guess you did receive lots of replies regarding your problem and you probably know now that there is newbie restrictions on putting signatures. The copper membership is a good one to bypass this aside from waiting and being active here, so make your choice.
It is more common for business's representative accounts to buy Copper membership and start their posts easily with graphics, images. It's less common for people who are not from any business to buy Copper membership, there are but not too popular.