You may want to start by reading the Manual, which contains a tutorial with examples. For more, and more detailed, examples, see this, this, or this.

The examples may be searched from a web page. This requires that python be installed, and a web server (say Apache) be running. Both python and Apache are free.

If you have no web server, you can run the python script XDXF_query.cgi from the command line:

python XDXF_query.cgi -d XDXF_dictionary -s search_string
The search result will then be written into a file called XDXF_query_result.xml, which you can open in your browser.

If you want to search your own XDXF dictionary, first you need to run the XDXF_indexer.py python script on it:

python XDXF_indexer.py your_XDXF_dictionary
Indexing must be done every time after the dictionary file is edited, even if the changes are cosmetic only.