Having trouble building a string and adding it to an insert parameter.

I'm having trouble building a string and adding it to an insert parameter. I am (or at least am trying to) loop through the contents of a listbox, build a string w/each value from the listbox, and then want to add that string to an insert parameter for a stored procedure.
 I can't for the life of me get this string to build and then add to the insert parameter. Any help is appreciated.

 This is what I have:
 
protected void btnAddProfile_Click(object sender, EventArgs e)
{

sdsInsertProfile.Insert();

for (int i = ListBox2.Items.Count; i >= 0; i--)
{

// create and open a connection object
SqlConnection Connection =
new SqlConnection(Conf ...