All you need to do is issue an SQL query:
SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
So a basic way is:
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand com = new SqlCommand("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES", con))
{
using (SqlDataReader reader = com.ExecuteReader())
{
myComboBox.Items.Clear();
while (reader.Read())
{
myComboBox.Items.Add((string) reader["TABLE_NAME"]);
}
}
}
}