I cannot find anywhere where I am meant to put the programs I download. Can someone help?

Thanks,
-Pinto

If you mean installing Scarpet apps, there is a wiki article here.

If you mean how to install Carpet mod or Carpet extensions, you need to install Fabric and then add Carpet (and extensions if desired) into the mods folder.

yeah, wiki page covers it pretty well - tldr - create a folder 'scripts' in your world and plop them there.