I already spent 6 hours I think finding how to put the mod in my launcher not for a server and it ends up with man crashes and I'm not used to technical stuff...

Which Launcher are you using and which crashes are you getting (full logs/crash report)?

well, I'm using the normal launcher or the Minecraft launcher and its fabric and version is 0. 14.21-1.20.
and about the crashes, it says crash game exit code 1 and if I try to get in the game it doesn't give a crash notice but nothing I check in task manager and other stuff but nothing I can see I dunno if I mess up up the java argument or it is something else since I got confused how to put the mod in fabric so the mean time I use pipe blocker since I have no clue what to do.

For the Vanilla MC Launcher you need to do the following:

• Download the latest SiB version from Github releases

• Open the game directory of your installation profile
  

• Move the downloaded SiB jar into the directory that was opened
  

• Open the settings of your installation profile
  

• Click on More Options at the bottom

• Add -javaagent:serializationisbad-1.4.jar at the end of the JVM Arguments (make sure that you have a space in front of the -javaagent:xxxx if there's already something in that input field)

• Click Save and start the game

somehow its not working i dunno what's wrong with it now. don't worry im not at all compromise. from the exploit.

ok now it say this