Can someone tell me where to go to get a good visual reference to grass types native to southtexas,my lawn is ugly I have crabgrass and I don't know what else,But to get the right treatment to kill the weeds I need to know what type of grass I have.How do you tell?

The question really isn't 'what type of grass do I have', but 'what type of soil do I have'. You change your grass when you put down the proper soil to support a good lawn. There are probably many types of grass within your lot, plus weeds. If you want to have a good lawn, you are going to have to remove what you have, or top dress with good soil to a depth of a foot and resod, or seed with a seed appropriate for your location.