Eyefinity configuration should be part of the Catalyst Control Center software. I have not used it on a laptop but here is a shot from my desktop
Your notebook may not support the required disaply output (see AMD FAQ). Check with HP support but that may be the reason that it is not showing up.
Yes! AMD Eyefinity technology support is also built into many of our notebook GPUs, but it is up to the manufacturer of the notebook to equip their product with the necessary display outputs.
Notebooks that offer the outputs to activate AMD Eyefinity technology include the Alienware M17x and the HP ENVY 17. Please note that the default configurations for these notebooks may not include AMD Radeon™ graphics, so be sure to verify that you have selected an AMD solution before checkout.