Hi! I am a newbie here...
Thank you for your work.
I am wondering is there any link that can show me how to install it?
Any lead is much appreciated.
Look at my signature or the first post of this thread, there's a link to my GitHub. Go to the releases tab and download the latest version of PSSE. You don't have to install it, it's a .exe you just have to run.
As it's a PC program, you'll need a way to launch homebrews on your 3DS to export/import your savefile. If you do, just use homebrews like JKSM or svdt to export your save, then insert your SD card in your computer or use microSD management to transfer the savedata.bin file to your computer. Edit it with PSSE then do the same thing backwards to import it back into your Shuffle save.