As stated above the letter "H" is only used in Gaelic to change the sound of the letter before it (lenition). This concept should be easily understood by English speakers as the language is full of the same stuff, and only the phonics are different. CH in English as in church and in Gaelic as in loch. Other English words like enough the gh becomes an "F" . In telephone ph becomes an "F". In Gaelic words mhor the mh becomes a "V" and in bheag the bh becomes a "V" as well etc.
Nach eil e doribh? :-}
          Slainte,
                Sandy