Try:
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand com = new SqlCommand("INSERT INTO myTable (myColumn1, myColumn2) VALUES (@C1, @C2)", con))
{
com.Parameters.AddWithValue("@C1", myValueForColumn1);
com.Parameters.AddWithValue("@C2", myValueForColumn2);
com.ExecuteNonQuery();
}
}