how to draw in Acrobat?

I know this is probably not the right place for that but...
I am developing a Asp.net app that deals with PDF forms. I have learned how to do the entire javascript on PDF documents, how to submit FDF data to my Web form, how to work with that data withthe Active X FDF toolkit, and fill form fields with data coming from my app.
Good.

I need to know how do simply draw 1 line in Acrobet. Or is this not posible in acrobet?

I have a form with whioch I am working and I dont lik the design. I want to add 1 litle black line in 1 place. That black line has to be part of the form design, the drawing behind the fields, but not part of a the collection of fields.

I cant seem to figure out how to do this...

I work with acrobat 8.1.2

Thanks