I firmly believe that my catalytic converter has.

I firmly believe that my catalytic converter has become clogged due to driving the car around for years with bad O2 sensors. I went the cheapo way and bought a cat from ebay. I think im pretty mechanically inclined since I have done a few repair jobs on my car myself such as replacing the alternator, replacing a bad serpentine belt on my A/C compressor, and changing my valve cover gasket along with a few other things. I was wondering if anyone could help with directions as to replace my catalytic converter. (The front one that comes directly from my exhaust manifold). And yes the cat I bought came with new studs, washers, and bolts since according my brother shops tend to break these when trying to get old cats off. Just looking for some information before I can decide if this is something I can tackle in my garage rather than spending another $200 just in labor costs at a shop. Thanks in Advance!