You have to apply for the airdrop, after that you have to write in their thread in bitcointalk (characteristics of the pc which you want to use for mining), they will respond in the thread and you will receive email. After that the mining tab at the dashboard on their site will be green (you can mine), so you only have to press the button mine. It's super easy and you don't need to install anything on your pc.
pp. you can mine with pc, laptop and smartphone