I have a Sipura SPA-3000 and I don't know how to setup it to work with my Skype account. Do I need any other software adapter to do this? Please help!
Thanks.

Skype uses proprietary format, so it is not compatible with any device that is not "associated" with skype brand.

You can use an Asterisk server and there is toll that connects Asterisk to Skype. So you can connect to SKype with your sipura via asterisk.