Go into the forum preferences page, and in the posting .sig box, enter your text; for example "join team DSL Reports and find Seti." Then check ".sig default is show." The default then becomes a time saver when you want your sig to show, and there is an option for you to de-select it any time you are composing a post where you don't want it visible.
You cannot include a ? in your sig. This is an anti-spam measure.