I have a website and I want to sell some books from different authors. Can anyone suggest who I should contact to get the legal rights to sell the books? I am selling them to other countries as well, so the prices would be different. I just want everything to be legal.
IANAL, but when it comes to rights, it is generally the the right to make copies that is protected. If you own an existing copy of a book you can sell it just like you can sell a chair or a piano.
However, the Supap Kirtsaeng case makes things a little more interesting. Publishers often sell books much more cheaply overseas than in the US or other first world countries. Supap Kirtsaeng was a Thai student who started a site that bought textbooks at local prices and sold them to US students over the web, greatly undercutting the publisher's US prices. The publishers sued, claiming that copyright law gave the the right to set prices in different markets. According to this Ars Technica story, its appears that the supreme court disagrees: https://arstechnica.com/tech-policy/2013/03/thai-student-protected-by-first-sale-supreme-court-rules/ Obviously, though, it is a case you should educate yourself on before you proceed.
The only right you need is to own the book that you are going to sell.
If you only had a license, not ownership, or were renting a book, then you could not sell it at all legally.
Those overseas books that competed with the US publishers were generally pirated and printed in violation of the copyright protection. So you should also be sure that the book you own that you plan to sell was published legally.
Your bigger concern will be how to sell enough books at a price that you make a profit. Advertising and marketing to get people to buy books from you is not free. It takes time and money to order, warehouse, then fulfill by packing/shipping books to the buyer.
Books are not a high profit margin business. Publishers sell at big discounts to people who buy in quantity like distributors, and in turn they give discounts to dealers, who in turn often discount books to help sell them. You would need a solid business plan to ensure this venture is viable for you.