The only way to search your local multiple listing service is to work with a real estate agent. The full MLS is only open to people who have valid licenses.
There are various services that claim to provide MLS searches for people who are not real estate agents, but they are often not accurate or comprehensive. If you only need general information about the home, you can also search public listings sites, such as Realtor.com or ZipRealty.com. These sites usually provide plenty of information for the average buyer, but they leave off private information that the actual MLS contains, such as when the house is empty.
Buyers and sellers who do not want to be represented by a real estate agent but need access to the MLS can sometimes find a discount broker to help them. These are licensed real estate agents who are willing to accept a small fee to list a property for sale or run an MLS search.
When you ask your agent to run a search, you can request more detailed information than agents usually provide. The MLS contains information about homes that have been sold or have a sale pending that many agents do not disclose unless asked.