How do you transplant a full grown tree?

First and foremost, consult an arborist re: specific trees for your area, in the size you want. Given your heat, you may be limited for options. Secondly, if the tree is larger, the planting site needs pre dug and tested for drainage. Lastly, you may need a company specializing in this service, as a crane or special equipment to dig the site / lift the tree and set it into place may be required. If water may be a concern (too much or too little for the tree's size), factor this into your choices.

depends on the size and species of the tree -- I recommend contacting a certified Arborist -- http://isatexas.com/ this is probably not a 'DIY' project