Where is oxygen sensor situated?? and how do I replace it? (honda crx delsol 1992)

 

You needed to make a new thread for this??

Its on the header/exhaust manifold - the only sensor there, pre-catalytic converter
Get a 22mm wrench or o2 socket, unplug the connector and take it out...simple
Use your head, some common sense, and you can handle this on your own