Navigating through directories, where can I store the path?

I am pretty new to asp.net..

I am developing an image gallery without database, the one online didn't work for me because I need many other features.
Anyway I have developed a backend already and navigating through directories using TreeView control, and storing in each node the dir Name as text and the full path to it as a value.
 But the frontend is causing me some pain.
I want to show the current images and names of sub directories inside the current one and an UP button to go up.
Where shall I store the path?
  
1 public void fillFolders(string Folder)
2 {
3 string[] dirs = Directory.GetDirectories(Folder);
4
5 foreach (string dir in di ...