Are you talking about the IRS, The State Controller or the County Tax Assessor. There will be different sites for the different ones.
The courthouse steps ( as they say) is the first place to look , but you do have three big auction companies that take care of many of the tax sales for some of the counties in Texas. I would bring up the county on Google and start my search there to see how they handle their sales. If I lived in the county I would go to the courthouse and read the wall.