Hi, if you want to insert a link to your sidebar I think the correct way to do it is to get a php/html/text plugin that will allow you to insert the link in the sidebar as new widget. You can try this plugin.
Install and activate the plugin then go to widgets and include the widget in the correct sidebar then include your link (you can have a title for this but it’s not required).
Hope this is it.
Regards
Drag a text widget over to the sidebar and enter it in as html.
e.g.
Click here
Just place the page id in the a tag (In the example above the page id is 110)
Hope that helps