Letter "ь" does not makes its own sound. Normally it modifies the consonant sound of the previous letter (makes it palatalized or "soft"). Looks like you need some very basic textbook.
Letter "Ы" roughly is the same as "И" but "И" palatalizes previous consonant while "Ы" does not.
It is very difficult to describe pronunciation by written text, better is to hear. There were some sites, which provide sound play for the pronunciation of words. Maybe someone can give a reference.