Finding Ebooks to Promote & Publish

Hi,
first of all, I apologies for using you 'self publishing form' for my question.

I have only recently opened an ebook store and I am searching for quality ebooks of all types to promote and sell. I am relatively new to the internet and I'm not sure how or where to get this material. Should I contact the authors directly? Can you give me any advice please?

Best regards,

Richie.