Put the .el file into a directory in your LoadPath and add the following to your ~/.emacs file:
(autoload 'enform-mode "enform-mode" "A major mode for editing Enform files." t nil)
When you are visiting an Enform file, use ‘M-x enform-mode’ to activate the mode.
For best performance you should byte compile .el files but it’s not required. A CompiledFile usually runs faster. There should be no warnings when compiling this file.
See TandemNskSupport for a method of automatically recognizing the language of Tandem files since they don’t have an extension and coders often can’t stick an -*-enform-*- comment in line 1.