Where do i find the oxygne sensor in my 1997 oldsmobile 88?

Should be 1 right where your exhaust pipe bolts onto your exhaust manifold and 1 after the catalactic convertor on your exhaust system

It is on your exhaust pipe-most vehicle have at least 2 o2 sensors so you need to find out which one is bad
ex-o2s1/o2s2/ho2s1/ho2s2
these are all descriptions for your o2 sensors when you pull the dtc code(check engine light)