To run it or open it, you may double click, otherwise, simply singe click and highlight it. Then select the task to perform. To rename the folder or file, you click on the box with the name, then click again. The name will now be highlighted, and the cursor is blinking. Simply type in the new name, the old one will disappear, and the new one will be created.
All file names have extensions.
Change extensions with care. You may destroy the utility of the file by changing the extension. Click View tab at top of panel. Browsing for folders and files with Open, Save, Save as, etc. In most programs it is unnecessary to type in the extension.