Hi Lara,
Before you start leaning any language you must ask yourself these important questions:
In what way the language I am going to learn is different from my native language.
ex: Hindi is derived from Sanskrit and uses most of its grammatical constructions. I am learning Russian and I find so much compatibility between the two in terms of "cases". Verbs, nouns, pronouns, adverbs, adjectives these all inflect with respect to tense, gender and voice.
Coming to your question of "ne". It has nothing to do with past tense. “Ne" is a nominative suffix added when the action is in active voice.
I know how difficult and complex it gets when you start reasoning about grammar rules, but that is the beauty of language.Is n't it?