Write a procedure to deal with a string

I want to do something like this:

dcl-s mystring char(50);
mystring = right('ABC1234');

and "right" returns a string that is 50 characters long with ABC1234 right
justified. I Can code the procedure, but how do I define my dcl-proc and
dcl-pi so I can send in a constant and return my value to mystring?

I've been googling and saw *CONVERT and some other things but I can't get
it right.

Thanks for any help.