The short forms of the adjective нџжный are used to express a need, such as 'I need pencils.' It is used with a Dative form of the person who needs something, and the Nominative form of whatever is needed.
Caution: Watch out for the stress in this short adjective: нџжен, нужнђ, нџжно, нужнІ.
Also note the government pattern: the syntax of the sentence Мнљ (Dat.) нужнђ крђсная рџчка (Nom.) is like English 'For me a red pen is needed', but the better translation is 'I need a red pen'.
Мнљ нужнђ рџчка. I need a pen.
Мнљ нџжно винћ. I need wine.
Мнљ нџжен карандђш. I need a pencil.
Мнљ нужнІ кћльца. I need rings.
Чтћ тебљ нџжно? What do you need?