How do i get 2 I P addresses

Hello,
I am getting a job online which i have to have 2 IP address. I called my DSL provider and they said They only provide 1 unless i want to pay for double internet. I heard maybe a router? I have the router i pay for monthy through my internet provider. WHy would i need another one and How does a router work? would i hook up to this router i have? Can i buy one used on the internet I have found some Lynski routers cheap on ebay. WOuld that work and how to hook up thanks Danielle