Open this link: http://www.mediafire.com/file/po4g8ir9g8dg3o9/Paint+Tool+SAI+Anglicised+with+Custom+Brushes+and+Transparency+Mod.zip
1: Download a program to open zip files if you don't already have one. There's a program on the page you can download to use and delete afterwards.
2: Click the download button.
3: Wait forever. Seriously, it's a big file. It's going to take a while.
4: Find it once it's done. It'll usually end up in your downloads folder.
5: Right click and choose "extract all"
6: Choose somewhere you can find it later. The default is usually the downloads folder. Choose "browse" if you want it in a different place.