1) Get data from your database and fill it to datatable like dtCollege
SqlConnection con = new SqlConnection("");
con.Open();
SqlCommand cmd = new SqlCommand("select * from College", con);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dtCollege = new DataTable();
da.Fill(dtCollege);
2) set two properties of your dropdown list
ddl.DataValueField= "CollegeCode";
ddl.DataTextField= "CollegeName";
ddl.DataValueField= "CollegeCode";
ddl.DataTextField= "CollegeCode";
3) then assign data-source to your dropdown
ddl.DataSource = dtCollege;
ddl.DataBind();
4) Finally code looks like this with "----Select College-----"
SqlConnection con = new SqlConnection("");
con.Open();
SqlCommand cmd = new SqlCommand("select * from College", con);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dtCollege = new DataTable();
da.Fill(dtCollege);
ddl.DataValueField= "CollegeCode";
ddl.DataTextField= "CollegeName";
ddl.DataValueField= "CollegeCode";
ddl.DataTextField= "CollegeCode";
ddl.DataSource = dtCollege;
ddl.DataBind();
ddl.Items.Insert(0,"---Select College----");
that's it, your dropdownlist is bind with your database table data.