Many schools have a spring application deadline for fall admission. That probably means you have to submit everything no later than March if you want to attend college in September. Check with the school you're interested in for exact deadlines. They're usually on the school's web site, or call the office of admissions. The Application Applying to several schools is often tedious and time consuming.
Some schools have their own applications.
Find out if you can use the Texas Common Application or another electronic application to cut down on the paper work. But however you apply, you need to research the information you'll enter on your application. Your application will make your first impression for you. Being late won't make a good first impression. Answer all questions.