How do I put a panel in the dopesheet header or complet the dope sheep context menu?

Good morning, sir,
I’m starting in python blender and I wanted to know how to add a panel in the header of the dropsheet or its context menu. I know how to create a panel and a menu but I’m wondering how to target one that already exists.

import bpy

class PanelTuto(bpy.types.Panel):
    bl_idname = "DOPESHEET_PT_panel_tuto"
    bl_label = "Panel tuto"
    bl_space_type = 'DOPESHEET_EDITOR' #PROPERTIES
    bl_region_type = 'HEADER' #"WINDOW    
    
    def draw(self, context) :
        l = self.layout
        c= l.column()
        c.label(text ="Panel tuto start!!")
        c.prop(context.object, "location")

def register():
    bpy.utils.register_class(PanelTuto)
    
def unregister():
    bpy.utils.unregister_class(PanelTuto)
    
    
if __name__ == "__main__":
    register()

Good day,

Menus let you append (or prepend) draw_functions to them…

def YourFunction(self, context):
    self.layout.label(text="Place Your Function Here")

bpy.types.DOPESHEET_MT_context_menu.append(YourFunction)

Check the ‘Addon Add Object’ Template, as it shows how to add a function to a menu (the add_object_button)

Thanks you, I’m starting to get a better understanding of how it works.