after you get cydia access it.
go to manage
go to sources
go to edit in the top right
go to add
type http://mc2.iphoneall.org/
the hit done
now go to search in the bottom right
search for installous and install it
that is used to download stuff directly onto your itouch

now go to safari (web)
go to appulo.us/appdb/i/
i suggest you bookmark this site
now search for the app that you want to download and click install and it will install it for you and it is free

if you have any questions let me know