How to I obtain a 4GB Ram?

I'm trying to play the new "crazy craft evolved" mod pack in minecraft but I need a 4GB Ram and I only have a 1 GB, I only have 68.8 GB used out of 931 GB on my pc. So how do I get a 4 GB Ram?

You need new computer my cuzzy…

The memory needed is the physical RAM in the system, not storage space.

You need to either buy more memory. If your computer is so old that 1 GB is the most it can handle, then you'll need a new computer (most come with 8 GB to start now.)