Or you can set the Datasource of the combobox and populate it directly from a datatable, for example:
cbCountry.DataSource = CustomSQL.GetCountryList
cbCountry.DisplayMember = "Country"
cbCountry.ValueMember = "Country"
cbCountry.Text = cbCountry.Items(226).ToString
This example populates a combobox with a list of countries from a datatable returned from 'CustomSQL.GetCountryList' and then preselects UK (item 226 in the list) as the text.