Your plea is a common one on here, seems National RV owners never sell them with the manuals!
Try here: National RV Archives
Sadly, many manuals aren't worth the paper their printed on. They are often very generic, cover many models, and don't give details like, "The Auto Transfer Switch is located under the foot of the bed." or the like.
First, start by using the Teal colored search box, powered by Google, to search for '2001 National Tradewinds LTC owners manual
.' You might get lucky. Then go from front to back in your RV, writing down make and model of every system you have. Then use Google to search for manuals for each item in your RV. Most are available on line with install, use, troubleshooting, and parts lists.
Finally, if you don't find your particular manual, read a couple for other brands of similar vintage. They will give you ideas on what you have and how to use it.
Winnebago Industries Operator Manuals
Coachmen RV - Manufacturer of Travel Trailers - Fifth Wheels - Tent Campers - Motorhomes