How can I retrieve an user's Instagram Id on my website of people who logged in?

I want to create a website where people first login with their Instagram account and then their user-id is saved in a database to unique identify them. I don't know PHP or HTML (my knowledge is limited to java and C), I need to use Instagram API, but I don't really know how and even looking around I can't find a good solution. Can someone point me in the right direction? Thanks in advice!