The Dallas County Elections web site has an online form for finding precincts. Fill out the fields as best you can -- you need at least your street number, street name, and zip code -- and click the "submit" button.
The results page shows your voting precinct number underneath the address you typed in. The voting precinct number is linked to a pdf map of the area covered by the precinct, so you can check that to be sure the system found your neighborhood. If the map is of an area where you don't live, check that you typed in your address correctly and that no numbers were transposed in the zip code or street number. Some streets have an E. or W. designator; be sure to include that as well.
After the precinct number is the upcoming election information section. This links to another page on the Dallas County Elections site with up-to-the-minute information on procedures and polling places. Following the election information section is the list of representatives specific to the address you typed in to begin with. It includes your city council representative and local school board member as well as state legislators and others. To find out who represents you in the U.S. Congress, go to the state of Texas web site.
Whether you're going to be out of town or just don't want to wait in long lines on Election Day, early voting is just as easy as voting on Election Day. Polling places will be listed on the Dallas County Elections web site. Take your voter registration card and go to the polling place during the times listed.
Early voting by mail is also possible if you will be out of the county during the early voting dates and election day, if you are sick or disabled, 65 years of age or older on election day, or if you are confined to jail, but eligible to vote. Apply to the early voting clerk for a ballot or use this online form on or before the seventh day before the election, but after the sixtieth day before the election. Be sure to mail in your ballot so that the early voting clerk receives it by 7 p.m. on election day.
The exception to that rule is if you are mailing it from outside the United States -- then you must mail it by 7 p.m. on election day and the early voting clerk must receive it by the fifth day after election day.