Ask other high-quality websites to link to your website.
Publish your website details in high pr press release sites.
Post some high quality content in good article directories and take a backlink from them.
Or hire some expert from SEOclerks.
Page rank for a website can be increased by building good content and also by backlinks from other high page rank webpages. They are of no value today as Google has stopped updating their page rank update since the past two years.
To increase page rank of website, you have better and quality backlinks. And to get quality backlinks, you have to try all major off page techniques in high PR sites so that you can get quality backlinks.