Anyone know how to take text from a file and place it in a HTML textbox using PHP?

for example i have a file called bob.dat and I want to load all the data in that file and place it in a "text area" object on an html page so the user can edit it and then save it back to the file.

saving information from the text area object to the file is easy...and loading the file is easy...i just dont know how to get the data from the file to the text area box...