Hi,
You are allowed one signature with your account. People who pay for plus accounts are allowed 5 extra. So, no, you don't have to pay to have a signature.
Adding a signature can be found under your
Control Panel which is at the top of the screen. When you click there you can scroll down and find
Main Configuration. Under that menu choose the edit button next to
Personal Information, email, password, etc. You will see a box called
Signature. This is where you would paste the image information. Generally it is the tags: <font class="small">Code:</font><hr /><pre>
</pre><hr /> The image may be 600x125 and up to 50k in size.
There are a number of siggy makers on the forum so I'm sure you can post in one of their threads to ask for a signature.
Hope that helps.