http://nm.msf-usa.org/msf/ridercourses.aspx?state=NE Manuals: Clymer is okay--well-suited for most uses. A full Honda factory manual is better, but then good luck finding one. In any case, get one or the other--you will learn much about your bike by reading, reading, reading.
http://www.clymer.com/Book.aspx?bid=514&title=Honda+CB550+and+650+Nighthawk+Repair+Manual%2C+1983-1985You do not want to download a manual. You want a full book, that you can flip through, keep in the garage, get greasy, write and tuck notes in.
Be aware the there are many useful subforums at this site (engine, suspension, braking, etc.):
http://nighthawk-forums.com/index.php#4 <--This is simply the parent forum to the one we're on now.
Above all else, make sure that you have good tires. How old are the ones currently on the bike? If they're older than 4 years, you should replace them. Tire rubber dries over time, losing elasticity and grip. You do not want to test this.
David Hough's
Proficient Motorcycling is an invaluable book, and a classic:
http://www.webbikeworld.com/books/proficient-motorcycling.htm