Im putting in the base of a 32" shower and need to now how to do it as well as do I need to replace the walls or can I replace the base only?

Unless you can repair the old base you'll have to replace both the base and enclosure.
Here's a link to click on to check out 32 X 32" shower base and enclosures.
32 X 32 - Google Search (http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLM,GGLM:2009-22,GGLM:en&q=32+X+32%22+shower+base+and+enclosure)
Good luck, Tom