When you enter the command "whereis perl" it will show you all the places the system can find 'perl'.   If you enter "which perl" you will see where the system thinks it should execute 'perl' from.   I bet none of these are where you put your copy of perl.

Where _did_ that copy of Perl get put, anyway?   You might want to use "find . -iname 'perl*'" at some likely starting points.   Once you find it you can try "export PATH=/that/place/you/found/it:$PATH" to put that into your path so the system can execute it from there.   At that point "which perl" should show you that Perl was found where you put it.