Hi,
You should just be able to add a hyperlink to your icon that links to your form template. Depending on the web part you have, you may or may not be allowed to add hyperlinks directly in your controls. If not, you might need SharePoint Designer.
And then of course, you'd need to know the location of your HR form template.
If your form is not browser-enabled, you can grab the URL in your HR Library page > Settings > Form Library Settings > Advanced Settings > Template URL. Prefix your SharePoint site URL to the relative URL you see in that page. It would be something like: http://YourSharePointSIte/Forms/template.xsn.
If it's a browser-enabled form, you must have uploaded the template via Central Administration where the URL would be something like: http://YourSharePointSIte/FormServerTemplate/YourTemplateName.xsn.
Hope that helps!