Please help! psd setup issue

[Topthat64]

Hi guys,

I'm a designer with zero developing knowledge and I'm having trouble with the DPI

I'm designing an app for Samsung 3 only and wanted to check with you guys if I have the photoshop file setup correctly?

I'm confused about the dpi issue. Do I leave the resolution at 72 and just increase the canvas size to 1280 x 720.

Thanks in Advance