setup of lan between laptop and desktop using D-Link DSL-2640U

Hi,
i have D-Link DSL-2640U , one desktop and lenovo laptop. I want to connect both the pc for lan. Which is the best method to connect them directly through lan port?
or using D-Link DSL-2640U for connection(Can disconnect net cable for offline)

also what type of cabling should be prepared?
cross or straight?

also provide some guidelines in this matter so i can do it myself. thanks