Great start to your home search. You are doing your research.
As other agents have answered,you need to find a lender. Most realtors can recommend several lenders to work with and it is as easy as filling out a credit application over the phone. This allows you to focus your search on homes within your price range. Once you have a price range, a realtor can help your define your search showing you homes that include any "must haves," as well as location. Searching online allows you to see what is out there, but a realtor can maxmize your time showing your homes that meets your criteria. Often what is not seen on Internet sites are the terms required to purchase homes (cash only, 203K, Homepath approved, etc.)
Lender pre-approval also allows you to write an offer that will be seriously considered by a seller. Without it, many sellers will not even consider an offer. Pre-approval demonstrates your capability of moving forward on the purchase. In this market, if a home is in good condition and priced right, it is going within weeks - yes, weeks. You need to be able to write an offer if you find one of these homes.
Good luck and if I can answer any other questions, please contact me.