You were probably awarded spousal support, as there is no such thing as alimony in Texas.
You will want to hire an attorney, as the only way to get him to pay is to ask nicely, or sue him. The attorney will probably file a motion to enforce the order, reduce it to judgment and then go after his bank accounts with the judgment.
I agree with Mr. Tisdale. To add to his answer: Texas courts will usually award attorney's fees to the movant of a motion to enforce. However, it is NOT easy to collect on a judgment against an individual in Texas. Most individuals are "judgment-proof" in Texas.