Сегодня утром (no comma needed) я решил перевести (perfective - one-time action intended to be completed: "решил переводить" is in general, e.g. every day; "решил перевести" - this specific occasion) два стихотворения ("два стиха" is used, but it is too colloquial, considered to be not quite correct, and not so good for this style of writing) (although if you intended to sound so informal, you may keep to "два стиха").
Некоторые части (часть - части, soft stem) стихов было трудно переводить. (Here, "было трудно" is not related to "некоторые части", therefore it does not agree with it. It is more like "It was difficult to translate some parts fo the verses". So, the subject is absent here (in English there is a dummy subject "it", the predicate is "было трудно" (neuter, because of the dummy subject), and "некоторые части стихов" is a direct object but not a subject).
If you wanted to say "Some parts of the verses were difficult to translate (for translation)", it is: "Некоторые части стихов были трудны для перевода". Now, "некоторые части стихов" is a subject, "были трудны" agrees with the subject, but you cannot use the infinitive here in Russian, you need a verbal noun instead: "трудны для перевода".
Вы можете помочь мне? (perfective - one-time action intended to be completed: "можете помогать" is in general, e.g. every time I ask; "можете помочь" - this specific occasion).