Girls youth either play for the private school they attend that offers the sport, or they play for a public team in the Greater Houston Youth Lacrosse Association [GHYLA].
The age that girls can start playing depends on the team. Some start as early as 4th grade, some as late as 7th grade. Contact the team closes to you for more information.
Current teams are:

Private Schools [must attend the school to play]
View Girls Youth Lacrosse in a larger map
Teams, to update your website link, please e-mail the webmaster