How can bitcoin network track my assignments?

[Bitcoin]

How can bitcoin network track my assignments?

(Question's reason: How does the network know my current balance?)

First of all, I'm new to bitcoin and learning to develop, and this question is for learn and get help at my develop, not for insult bitcoin is bad.

How can bitcoin network track my assignments?
As I know, every assignments are hashed so no one can but only contract parties know about assignments.

But how can bitcoin network track my assignments? Is my knowledge 'only the contracting paries' wallet can their assignment' wrong?

Source: How can bitcoin network track my assignments?