How to Separate emails in CC by HTMl or javascript

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C#

ASP.NET

hi,
i wrote a web application with c# and Asp.Net to send an emails to multi persons
and i can send email to and cc (just one in the cc)
but i cant send to multi
another i cant put multi emails in the text box by HTML or JavaScript

and this is my Code

protected string toEmail, EmailSubj, EmailMsg,ccId,bccId;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (this.IsPostBack)
        {
            toEmail = txttomail.Text;
        EmailSubj = Convert.ToString(txtsub.Text);
        EmailMsg = Convert.ToString(txtsub.Text);
        ccId = Convert.ToString(txtcc.Text);
        bccId = Convert.ToString(txtBCC.Text);
        //passing parameter to Email Method
        SendEmail.Email_With_CCandBCC(toEmail,ccId ,bccId ,EmailSubj, EmailMsg);
        Label1.Visible = true;
        Label1.Text = "Email Sent Successfully";
 
        }
    }
   
    protected void btnreset_Click(object sender, EventArgs e)
    {
        txttomail.Text = "";
        txtsub.Text = "";
        txtsub.Text = "";
        txtBCC.Text = "";
        txtcc.Text = "";
    }