I just want to say "I need to find it", or "The main thins is that you will find it" (for example, the key, the document, etc.). Now I am not sure which verb is more appropriate to the context that I showed. Google translate showed me both choices for the word find: найти & находить.
Мне нужно это найти.
Vs.
Мне нужно это находить.
When the verb is transitive you have to use a perfective form in positive sentences, like in
Мне нужно это найти.
As suggested by Баян Купи-ка in the comments imperfective form is also valid here when you talk about some stretched in time duty:
Мне нужно находить решения, приемлемые для всех - I [always] have to look for solutions, suitable for everyone.
In negative sentences you use imperfective verbs:
Мне не нужно этого находить [, чтобы принять правильное решение].
When the verb is intransitive you can use both perfective and imperfective forms in positive sentences:
Мне нужно идти. Мне нужно уйти. - I have to go (leave).
In negative sentences you use imprefective verbs:
Мне не нужно уходить.
Notice that perfective/imperfective aspect is often connected with "transitiveness", so sometimes you have only one option.
If you need to find it once, мне нужно это найти. Example: you lost your glasses and need to find them as soon as possible.
If you need to find it time after time, мне нужно это находить. Example: you have a pet who takes things and hides them in different places in your home. You need to find the lost thing each time it happens.
