You may want to sign on here:
National RV Dolphin Forum - Topix
Usually to turn the chair, move it FORWARD as far as possible (I know, sounds counter-intuitive) and then release seat back until it is vertical or leaning forward a bit.There should be a lever under the seat to release lock so it pivots.
I'd also suggest if you don't have manuals, to write down the make and model of each item in the RV and then google the manuals. The manual from National is going to probably be a disappointment, they are full of generic legal blather and don't give all that much detail. You might be just as well served by one from this site as to general 'how to's.
Manuals & Diagrams
Your National manual is probably general enough to cover many models and features. If you need to know where the electric panel is, or where the chassis fuse panel is, it's probably better to ask someone on here.