How to get access to methods\controls in master page?

Question

ASP.NET

Hey!
A website consists of a master page and content pages.
The masterpage code file is as follows:

public partial class MasterPage : System.Web.UI.MasterPage
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //PopupAdd();
        }

        public void PopupAdd()
        {
            popupOverlay.Attributes.CssStyle.Add(HtmlTextWriterStyle.Display, "inline-block");
        }
    }

popupOverlay is a div block (if that matters).
There is a regular class, let's call it ButtonInsert , located in the app_code
folder Question:
How can I access either the PopupAdd () method or the popupOverlay div directly from ButtonInserta ?
MasterPage test =new MasterPage();
does not roll =( masterpage methods, does not see a freshly created instance of the class.
Thank you.

Answer 1

Build your own logic so that MasterPage asks something what to "draw" and in what cases. In general, MasterPage is needed as a template, there is not enough complex logic there.