Hello Donna!
You can get a bleached look to your pine paneling by painting on a white or cream gel stain directly over the existing finish. I would try that first, since its the easiest solution. If you want a deeper look, do a second coat after the first one dries. Do a small section of the wall to see how you like it before proceeding with the entire room.
If you do not get the intensity of bleached look that you want, then you will need to sand the existing finish (varnish or sealer) off all of the wood before staining. Staining directly onto the bare wood will give the stain the ability to seep into the wood and show the unique graining to best advantage. I like to use a round random orbital palm sander for projects like this. They usually have a little bag attached for collecting the dust, but it is still a very dusty, messy job. Be sure to tape sheets of plastic up to cover the doorways (so the dust does not go throughout the house, although it still will to some degree). Also, wear a dust mask to keep it out of your airways.
You could also use a chemical stripper, but that is even messier and can be rather toxic, so I suggest avoiding it at all costs.
I hope these ideas help you brighten up your space and give it a nice fresh look! Please let me know how it goes.
LB12star@aol.com