How can I set up the internal HDD on my iMac to be able to connect to it from my laptop at college?

To better explain my question and what I am trying to do...

my iMac is in my room in my parents house, and I want to be able to connect to my iMac's hard drive from about 300 miles away at college on my PC. Would it be possible to somehow set up the HDD via ftp. I know it is possible inside of local network to connect via ftp but I have never seen this be done outside of a local network.

If anyone has anymore ideas, videos explaining how to do this, or just simply knows the steps that need to be done to set this up please share.

If it helps, I am on my iMac right now.

Thanks