If you have ever used your machine to free hand darn or free hand embroider, you already know how to free motion quilt. If that thought makes you nervous, use a walking foot and work on smaller projects to practice free motion. You would need to do that on most moderately priced new machine.
If you have that green Elna, I remember my Aunt Lydia had that machine. It would do absolutely anything.
The walking foot keeps the layers on the quilt from shifting, preventing folds and creases in the finished product.