Learn Farsi: مهندس فایل‌ها را در شبکه بارگذاری نکرده است. - The engineer has not uploaded the files to the network.

To make it negative, you add the prefix نـ (na-) to the verbal part of the compound. For the present perfect, this prefix attaches to the past participle, making نکرده (nakarde). The non-verbal part (بارگذاری) stays exactly the same, and the helper verb است (ast) follows. Together, it makes بارگذاری نکرده است (has not uploaded).

The English translation says 'to the network', but the Farsi sentence uses در (in). Why?

Prepositions often don't translate word-for-word between languages. While in English we say we upload a file to a network, in Farsi, the convention is to put it 'in' a network using در (dar).

Why does را come right after فایل‌ها instead of at the end of the sentence?

The word را (ra) is the specific direct object marker. Its strict rule is that it must immediately follow the noun it belongs to. Since the specific direct object is فایل‌ها (the files), را goes right there, before the prepositional phrase در شبکه.

How is the English loanword for 'file' pluralized in this sentence?

Foreign loanwords like فایل (file) are almost always pluralized using the standard Farsi plural suffix ها (ha). Here, it attaches to the word to become فایل‌ها (files).