Try:
string basePath = Path.Combine(@"C:\Users\user\Desktop\Project\Project1\Test\Test\NewProject\StoreImage, panel.HeaderText);
if (!Directory.Exists(basePath)
{
Directory.CreateDirectory(basePath);
}
MyImageOfAChart.Save(path.Combine(basePath, "MyFileName.jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);