Hi there, does anyone have a tutorial (or can explain me) how can I turn on the input display on the SMB Pellsson Practice rom V5.6?

You need Simplistic's version of Pellsson. https://github.com/simplistic6502/smb

On the github, click the green "code" button, then "download zip". It should download a zipped folder. Unzip it and there is a file called smb-v5.6.ips. Use this website: https://www.marcrobledo.com/RomPatcher.js/ and under "ROM File" select the SMB1 rom. For "patch file" use the smb-v5.6.ips. Open the rom in an emulator and start the game. One you are in 1-1, press enter. A menu will appear. Use Select to move down to "Input" and A to change it to "On". Press enter to start the game again

Thanks, man, I just got it to work, I appreciate it

Any time