for the radio buttons to display the right one:
assuming the variable coming from the database is $sex (with values either M or F):
echo "<input type=\"radio\" name=\"sex\" value=\"M\"";
if ($sex = "M")
echo " SELECTED";
echo ">Male\n";
echo "<input type=\"radio\" name=\"sex\" value=\"F\"";
if ($sex = "F")
echo " SELECTED";
echo ">Female\n";
Then you'd just need an update button, and have the form's action as "update.php". Then in update.php you'd call an sql update statement to add the new value.