Help! Invalid Column Name

Question

As a beginner keen in learning C# database programming, I followed an example on YouTube. The followings are the steps:
1.
 Created a form with two text boxes, namely txtID and txtName
2.     Created a program. The part for creating the sql and sql command is as follows. 
3.    The problem: somehow when executing the SQL command (exeSql.ExecuteNonQuery();) it keeps saying Invalid Column Name, for example, if I enter "Edward" as txtName.Text, it says
Invalid Column Name "Edward"
Would somebody be kind enough to help?
Thank you very much!
Ed
 -----------------------Extract from Program --------------------------------------------
 try
               string sql = "INSERT INTO Students (Student_Id,StudentName) values(" + txtID.Text + "," + txtName.Text + ")";
               MessageBox.Show(sql);
                SqlCommand exeSql = new SqlCommand(sql, cn);
                cn.Open();
                exeSql.ExecuteNonQuery();
                MessageBox.Show ("Add New record Done!!","Message",MessageBoxButtons.OK,MessageBoxIcon.Information);
                this.studentsTableAdapter.Fill(this.studentsDataSet.Students);
-----------------------End of Extract from Program --------------------------------------------

Answer 1

Thank you very much! Indeed it works! I didn't realize that varchar without single quote became a name itself! You are very helpful! Thank you very much!
Glad to help. Please mark as answer if it solved your issue. Thank you
Fouad Roumieh