Multiple Checkbox Saving in MySQL?

[eluser]dhall[/eluser]
I have an array that I pass from Controller to View to create a list of checkbox options for the User.
Here is the view:

Code:

echo form_label('Secondary Activities:').br(1);
  foreach($all_activities as $row) {
    echo "<p class='activity_select'>";
    echo form_checkbox($row->act_type_id).nbs(2);
    echo form_label($row->act_type_name);
    echo "</p>";
  }

How do I take the selected options and save them into a database table to then allow for reposting once saved?
Sorry, I am new to all this stuff.