As you using WordPress so you can use so many plugins to improve your theme. You will find a lot of plugins in the plugin option of your WordPress dash board. click plugins and then write plugin for a widget on new plugin box. Then you will find a lot of plugins for add a widget.
Correctly insert the link including http://……….. or https://………….. It may create problem for http://…….. or http://www……. So check the link or URL and insert it with link building option of your writing box.
