regex replace in title format

Hi is there a way to transform Capitalized tittle to lower case tittle before passing it to the URL of the website you want to querry?

EG
my search is
[IndexUrl]=hxtp://blabla.net/page.php?moteurTitre&titreK=%s

with %s being Bon%20Anniversaire and i want it to be bon%20anniversaire

THX

Apparently this works:
[SearchBy]=$lower(%album%)

thx works fine anywhere to find a tutorial about writing websources dev?