How do I load list content into a template_list?

Question

I want to list some blend files from a folder in the UI. Reading the folder content already works. The output lands in a list. Now I need to display the content of this list in a template_list box. I am totally lost with this template_list.

My problem is basically:

mylist = []
...
row.template_list(what has to stand here to display the content of my list?)

So how do I get the list content into my template_list?

The as much as possible reduced script is at the moment in this state:

import bpy
import os


 # -----------------------------------------------------------------------------------------------------
 # the panel is in the properties sidebar.  
 # -----------------------------------------------------------------------------------------------------

mylist = []

class VIEW3D_read_dir(bpy.types.Operator):
    """Blubb"""
    bl_idname = "view3d.read_dir"
    bl_label = "Read Dir"

    def execute(self, context):

        mylist = [] # empty the list
        start_path = 'C:/Users/x/Documents' # current directory

        for path,dirs,files in os.walk(start_path):
            for filename in files:
                if filename.endswith(".blend"):
                    mylist.append(os.path.join(filename)) # fill the list
        print (mylist) #debugging
        return {'FINISHED'}  

class MyPanel(bpy.types.Panel):
    bl_label = "Testpanel"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'

    def draw(self, context):
        layout = self.layout

        layout.operator("view3d.read_dir", text="read directory") # Button to read the directory

        scene = context.scene
        row = layout.row()

        row.template_list("UI_UL_list", "keying_sets", scene, "keying_sets", scene.keying_sets, "active_index", rows=1) #Grabbed from Keying Sets to have a template list to play with


# ------------------------------ register unregister --------------------------------------------------------  

def register():

    bpy.utils.register_module(__name__)

def unregister():

    bpy.utils.unregister_module(__name__)

if __name__ == "__main__":
    register()