The first things to do are find a good place to ask questions (you've made a good start there at least), find some tutorial material (Tutorials will probably help) and find the Perl documentation which is available on line at perl. For regular expression help see perlretut and perlre.

Next you need to write a little code and see what you can manage. If (when) you run into trouble condense the problem down to a small sample that demonstrates the issue and ask us for help (we like to see evidence of a little effort anyway).

Remember to always use strictures (use strict; use warnings;) - they catch a lot of errors of all sorts earlier rather than later.

However, for your immediate task what you really want is the translation operator tr/// (look for tr/SEARCHLIST/REPLACEMENTLIST/cds under Regexp Quote Like Operators in perlop).