People who attract a lot of friends are neither negative nor needy.
Do I need to change this sentenance so that both parts are parallel?
No, it's fine as it is. It's already parallel.
"I am both a quick worker and careful." do i need to change this sentence to make it parallel?
People who attract a lot of friends are neither negative nor needy.
Yes, in order to make the sentence parallel, you can change it to: "People who attract a lot of friends are neither negative nor needy."
To ensure parallel structure, both parts of the sentence should use the same grammatical form. In this case, the original sentence used an adjective ("negative") and an adjective-noun combination ("needy"). By modifying the second part to also use just an adjective, "needy," the sentence becomes parallel.