I want to create a hierarchical view of my space as My Space > PageTree > Page

[archana]

I want to create the structure as 

My Space > Page Tree > Page for this I need to change the theme as per the process

1.  Go to the space you want to edit the Tree.

2.  Click browser -> Space admin 

3.  Look and Feel -> Themes

4.  Go into documentation theme configuration

5.  Un-select Page Tree

6.  Add something similar to the following to navigation

But when I go to my Themes, it shows the below error

Choose New Theme

To change the default theme of this Confluence site, select one below:

No themes could be found. If you have a theme plugin installed, ensure that it is correctly placed in the Application Server classpath, and that its theme module is enabled in the plugin configuration.

Kindly help

[Nic Brough -Adaptavist-]

I am not sure there is a question here.  If there is, there are probably two though.

First, you are talking about a tree structure in Confluence.  It does have a tree (formed by metadata on pages), so that you can nest pages, and have parent/child/grandchild type relationships and structure.  You can see these in the "reorder pages" space admin option, in the sidebar, and in page-tree macros.  I am not sure what you are asking about these trees though.

Second, you talk about themes.  A theme (heavily) customises the layout and view of Confluence.  Confluence now only comes with one theme.  You appear to be trying to swap to another one, but to do that, you need to have installed other themes.  "No themes could be found" is telling you that you have not installed any yet.  Have a look in the marketplace for themes, there are many, as well as theme engines, which are one app giving you many customisable (in the UI) themes.

There is a relationship between theme and the page tree in the side-bar - some themes, including the built-in one, allow you to turn the tree in the side-bar off if you want.

Hopefully, that explains enough to cover your question.  If it does not, could you explain what the actual question is in more detail?