First, decide on how you view belonging for individuals, depending on how important or insignificant you perceive belonging to be. Is belonging important for individuals, like the question states? Or do you disagree and view belonging as insignificant? This will be your thesis.
You then have to textually support your thesis throughout your essay; establish why belonging is important and/or insignificant for individuals by using both positive and negative consequences of belonging through your argument.
Whichever perspective on belonging you adopt, you still have to discuss both negative and positive aspects of this belonging, continually referring back to your thesis (which should be in the last sentence(s) of your introduction).
Positive aspects of 'belonging' could include:
* A feeling of acceptance, which positively alter one's outlook on life.
* A sense of interconnection with nature/people/etc, which allows one to further understand themselves (e.g. a connection with nature may be established by the protagonist's aesthetic liking of autumn, which reminds the protagonist of the transiency of their own life).
Negative aspects of 'belonging' could include:
* Sacrificing personal ideals to 'fit-in' with the majority, which can lead to self-delusion and cognitive dissonance (e.g. someone may be a particular sect of Christianity to feel a sense of belonging within the Church, even though the Church's view on women/homosexuality is completely against their own inner morals and ethics).
* Superficiality can arise from certain kinds of belonging, especially in the materialism of modern culture, which can lead to a loss of a identity (e.g. someone may feel a sense of belonging to a particular popular culture icon - such as Marilyn Monroe - and view her as a role-model for their own life, yet this sense of belonging is ultimately shallow).
* Also, someone can belong to a niche or sub-culture group, yet due to belonging and being a part of this particular group, they are essentially alienated from the rest of society (e.g. gothic sub-culture).
I would structure it like this...
P1 - Introduction (thesis)
P2 - A positive consequence of belonging
P3 - A negative consequence of belonging
P4 - A positive consequence of belonging
P5 - A negative consequence of belonging
P6 - Conclusion
