You might want to search the help documentation on Geocoding. Geocoding is a process by which you translate an address that we humans understand, think 1234 Main St, into a pair of xy coordinates that the GIS understands. Your locator is based on some sort of feature class, often road centerlines that has address data that you match your address table to. The help docs have a tutorial as I recall. Give it a go, and let us know if you get stuck along the way.
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