Are you taking lessons with anyone or working on your own? I would suggest lessons so you learn the safe way to teach obstacles. Your instructor (or the agility club giving the lessons) will have sturdy, safe equipment for you to use.
At this point, keep everything very upbeat and encouraging with your obedience work. (Don't forget to get her used to walking and trotting on either side of you for agility work. With obedience, the dog is on your left side only.) Dogs starting agility need to know 'come', 'sit', 'down' and 'stay'. Unless you have an enclosed area, I would keep her on leash for now. I wouldn't correct her at this point, just ignore any mistakes, show her what you want her to do and praise her to the skies when she even makes the attempt. Does she have a favorite toy that can be used as a reward? Will she work for treats?
I'd even be tempted to treat her as a puppy when it comes to obstacles. You can get PVC pipe (3/4 inch, about five ft. long) to use as jump bars, set them on cinder blocks for low jumps (you'll be jumping with her at this stage, being VERY happy when she comes over the jump with you.) A 4x4 piece of plywood balanced on a 4x4 post can be her introduction to the teeter (gets her used to a surface moving under her weight). A 2x8x12 plank balanced on two cinder blocks can be her introduction to the dogwalk. Be very encouraging at all times and end your sessions on a happy note with something she knows how to do well.
A friend has a rescued Italian Greyhound (he was taken from a puppy mill breeder). This little guy is afraid of his own shadow but after a lot of work (she never corrects him, just brings him back to do the obstacle he missed and continues on), he has actually earned himself a title in an agility game. She's the kind of handler you like to see, doesn't get upset if the dog takes the wrong course or knocks a bar - she's there to have fun with her dogs and her dogs are happy workers.