You would be wise to also direct this question to http://shop.lenovo.com/gb/en/laptops/ideapad/500-series/510-15-inch/
Generally speaking, if the laptop is equipped with an optical bay - which I believe is the case with the 510 - a HDD/SSD caddy can be fitted in the optical bay compartment. Understand there may be some warranty issues since a number of manufacturers look askance at this modification of their equipment.