Try this
string provider = ConfigurationManager.ConnectionStrings["databaseConnString"].ProviderName;
DbProviderFactory factory = DbProviderFactories.GetFactory(provider);
//Open Connection
DbConnection conn = factory.CreateConnection();
//Assign Connection String
conn.ConnectionString = ConfigurationManager.ConnectionStrings["databaseConnString"].ConnectionString;
//Connection Open
conn.Open();
//Initialize Command
DbCommand comm = conn.CreateCommand();
//Tell command which connection it will use
comm.Connection = conn;
//Give command SQL to execute
comm.CommandText ="Insert into userinfo(UserName, Passwrd, FirstName, LastName, Address, Address2, City, State, ZipCode, Email, Gender, Age, ShirtSize, PantSize, EmailSubscribe) values(@UserName, @Passwrd, @FirstName, @LastName, @Address, @Address2, @City, @State, @ZipCode, @Email, @Gender, @Age, @ShirtSize, @PantSize, @EmailSubscribe)";
SqlParameter userName = new SqlParameter("@UserName", SqlDbType.VarChar);
userName .Value = userName.Text;
comm.Parameters.Add(userName);
SqlParameter password = new SqlParameter("@Passwrd", SqlDbType.VarChar);
password .Value = password.Text;
comm.Parameters.Add(password);
SqlParameter firstName = new SqlParameter("@FirstName", SqlDbType.VarChar);
firstName .Value = FirstName.Text;
comm.Parameters.Add(firstName);
SqlParameter lastName = new SqlParameter("@LastName", SqlDbType.VarChar);
lastName .Value = lastName.Text;
comm.Parameters.Add(lastName);
SqlParameter address = new SqlParameter("@Address", SqlDbType.VarChar);
address.Value = address.Text;
comm.Parameters.Add(address);
SqlParameter address2 = new SqlParameter("@Address2", SqlDbType.VarChar);
address2.Value = address2.Text;
comm.Parameters.Add(address2);
SqlParameter city = new SqlParameter("@City", SqlDbType.VarChar);
city.Value = city.Text;
comm.Parameters.Add(city);
SqlParameter state = new SqlParameter("@State", SqlDbType.VarChar);
state.Value = state.Text;
comm.Parameters.Add(state);
SqlParameter zipCode = new SqlParameter("@ZipCode", SqlDbType.VarChar);
zipCode.Value = zipCode.Text;
comm.Parameters.Add(zipCode);
SqlParameter email = new SqlParameter("@Email", SqlDbType.VarChar);
email.Value = email.Text;
comm.Parameters.Add(email);
SqlParameter genderRadioGroup = new SqlParameter("@GenderRadioGroup", SqlDbType.VarChar);
genderRadioGroup.Value = genderRadioGroup.Text;
comm.Parameters.Add(genderRadioGroup);
SqlParameter age = new SqlParameter("@Age", SqlDbType.VarChar);
age.Value = age.Text;
comm.Parameters.Add(age);
SqlParameter drpShirtSizeCategory = new SqlParameter("@ShirtSize", SqlDbType.VarChar);
drpShirtSizeCategory.Value = drpShirtSizeCategory.Text;
comm.Parameters.Add(drpShirtSizeCategory);
SqlParameter drpPantSizeCategory = new SqlParameter("@PantSize", SqlDbType.VarChar);
drpPantSizeCategory.Value = drpPantSizeCategory.Text;
comm.Parameters.Add(drpPantSizeCategory);
SqlParameter emailRadioGroup = new SqlParameter("@EmailSubscribe", SqlDbType.VarChar);
emailRadioGroup.Value = EmailRadioGroup.Text;
comm.Parameters.Add(emailRadioGroup);
//Execute command get back result via reader
int totalCount = comm.ExecuteNonQuery();
DbCommand comm2 = conn.CreateCommand();
comm2.CommandText = "Select @@Identity";
comm2.Connection = conn;
String id = comm2.ExecuteScalar().ToString();
conn.Close();
lblMessage.Text = "ID of User Added = " +id;