how do I install an extension in wordpress
If you have CiviCRM installed on your WordPress installation as a plugin and you are inside CiviCRM trying to install a CiviCRM Extension.  This is what I do to had an extension that is not automatically available with CiviCRM Extension manager.  I go to my server manager CPanel and use the file manager to upload the extension zip file.  I place the extension zip file in to the folder;  public_html/wp-content/plugins/files/civicrm/extensions. Extract the zip file and the new CiviCRM extension will become available to install within the CiviCRM Extension Manager.