Your 66 takes ordinary 15x1 needles, also called 2020, 130, 705, HAx1 and probably several other numbers depending upon the needle manufacturer. The ordinary needle is available in
sizes from 9 to 26, but most of your quilting and piecing will be done with a size 11, 12 or maybe a 14.
When you set the needle, the flat side of the needle shank needs to face to the right and you need to thread your needle from left to right.
The 66 also takes ordinary class 66 bobbins which might even be sold at the grocery store - certainly at WalMart or Joann or Hancock Fabrics. My 66 uses plastic or metal with no trouble at all with either one, but some of the vintage machines don't like the plastic ones, so if you can get good-quality metal ones to begin with, those would be better.
When you set the bobbin, the thread should wind off the top of the bobbin from right to left - counterclockwise.
The manual is available online in pdf format:
http://www.singerco.com/uploads/download/41_66.pdf
Have fun! :)