There are several places to go to find out who your representatives in the Texas Legislature are. (Everybody has one each in the Texas House of Representatives and the Texas Senate, by the way).
The Texas Legislature provides a locating service at http://www.capitol.state.tx.us/fyi/fyi.htm (the "fyi" used to stand for "Find Your Incumbent," but the page is now simply called "Who represents me?"). You can search for your personal representative by entering your home address. Representatives can also be searched by city and county, which can be useful if your city or county is represented by more than one person and you want to visit/contact all of them. Be sure to note that senators and representatives usually have an office in Austin at the capitol and one or more offices in their home district.
If you already know who your representatives are, you can find listings for their district offices in the blue pages of your local telephone directory.
If you don't like web searches, you can also call the voter registrar for your county to ask who represents you. However, you will still probably have to consult those blue pages for contact information.