How to upload and save file with a unique random file name in ASP.Net

Hello,

I have a variable:

public static string ClientName;

And the code below which saves an image to a folder on server:

 public static void UploadPic(string imageData)
    {
        
        string Pic_Path = Path.Combine(HttpRuntime.AppDomainAppPath, "SavedSig/ClientSignature.png");
        using (FileStream fs = new FileStream(Pic_Path, FileMode.Create))
        {
            using (BinaryWriter bw = new BinaryWriter(fs))
            {
                byte[] data = Convert.FromBase64String(imageData);
                bw.Write(data);
                bw.Close();
            }
        }
    }

I would like to rename that file evrytime with the value of the variable