Backup files recusive

Hi,

I have folder , backup , with sub-folders Jan , Fev , Mar , witch also have sub-folders

How can i recursivelly compress this files , in each folder grouped by month?

Do you just want to compress, or would e.g. tar (or another archiver) come in handy?

i use 7z due to high compress range that it had, i have study all solutions available and this is the best one,
i had try few solutions , but problems i encounter is , compress archives by month in local directory where they are, that is the tricky part for me .....