Tomorrow is the deadline by which voter registrations must be turned in to county offices or postmarked if you are going to vote in the November election, and it is not like those offices or the post office are open at night (or at all today) , so you have less than two days to register!!!
Not sure if you are registered? Here is a link where you can check and get more information about registration.
Here is a link with information about getting registered in Texas.