There are many places where one can buy parts for a Honda Civic 96. The best places to buy parts would be at a local car parts store or at a Honda dealership.
Many parts are interchangeable between a 1992 and 1995 Honda Civic, but always consult a qualified automotive mechanic before trying to use these parts.
There are many store which offer parts for a 1997 Honda Civic. One could go to the local Honda dealer, or, alternatively, one could look on websites like procivic or breakeryard.
AutoParts.com and eBay carry a vast array of parts. Honda Civics are common cars so their parts should be easy to find. Some places to buy Honda Civic parts online are Majestic Honda (http://www.hondaautomotiveparts.com/) and Pro Civic (http://www.procivic.com/). They can also be purchased from sites that sell parts for many manufacturers such as Parts Train (www.partstrain.com) or Auto Parts Warehouse (www.autowarehouse.com).
Lucky for you the Honda Civic is a very common car and there are many websites offering replacement parts. The one that contains the most inventory of your specific needs is most likely www.thehondapartsstore.com as it carries exclusively Honda replacement parts.
2 ... one on top and one underneath the exhaust header
probably one located just after the engine on the exhaust. by now this sensor will be stuffed
The 2008 Honda Civic has 16 valves.
The 2014 Honda Civic has 16 valves.
The 2003 Honda Civic has 16 valves.
The 2010 Honda Civic has 16 valves.
The 2011 Honda Civic has 16 valves.