...Welcome to the internet. Interesting place to start.
Okay, so on the main page of this thread (the first one on page 1) you will find a section labeled 'Downloads' with a bunch of links to various websites. MEGA is generally the fastest and most reliable.
Inside you'll find a download page for a .Zip file. In order to unpack it, you'll need Winrar. It's *free* in that you can simply close its requests for you to buy it after the 30 day trial while still using it.
You must be registered to see the links
Once you unzip it to a folder wherever you want it, you have installed the game. Great! ...But it's still in Japanese.
On the main page, there's a couple of links below the game downloads. One is labeled 'Machine Translation,' the other is labeled 'Fan Translation.' You don't strictly need the Machine Translation link, because its contents are also in the Fan Translation link.
The Fan Translation link has its own tutorial built-in, so I won't repeat myself there.
If you have any issues, feel free to ask for help!