Adding 'Next' and 'Previous'-links to

Hey there.

Can anybody help me with how I add ‘next’ and ‘previous’-links to the <!--nextpage-->-function in the same style as what can be seen here?

The function as it is right now only gives you the option to click on the number of the page (eg. 1 and 2), but I think it would be a better option from a design p-o-v, if you could also just add a Next and Previous-buttons, that would only list to the page you are coming from or going to next.

Thanks