Hello Andrew,

First use a free button generator such as this one to create your download button (save it as a PNG image):

http://buttonoptimizer.com/

Then insert the PNG image on the appropriate page of your WebSite X5 project using an Image Object:

http://help.websitex5.com/en/v12/evo/index.html?ogg_immagine.htm

Then use the 'link' icon on the editing toolbar to set a hyperlink on the image pointing to the location of the software which is available for download (i.e. 'File or URL'):

http://help.websitex5.com/en/v12/evo/index.html?ins_link.htm

Please let us know if you require further information.

Kind regards,

Paul