

Decrypt the CIA (if needed), unpack the decrypted CIA, and rebuild as .3DS.

Do I have to use a 3DS portable to do this or I only need an Encryption ROMS and the program for a Windows and thats all???
Just follow the link above after decrypt the CIA ?? Which one should I use: Using Xorpads or without it ?
I want them to use for a Citra Emulator test purpose.
You still need to decrypt it beforehand, but to play with citra, you don't even necessarily need a 3DS file. It handles much looser than a real 3DS. It supports directly loading CXI files, so you can just `ctrtool --contents=contents <file.cia>` and rename the first content extracted as game.cxi and open that.

Yes, I understand but I am asking if I need 3DS portable to use the decrypted tools or I can use decryption tools on the Windows to decrypted the ROMS without actually 3DS ? Thats what I am asking.
tl;dr - No. You need a 3DS. Or xorpads someone has generated on one.
Long version - the keys on the 3DS needed to perform the decryption are inaccessible to us, and as a result there's no way to decrypt on a PC. We're capable of decrypting on the 3DS by treating crypto as a black box.
Sad truth.