Here is the text of Gay Science 290 (and here for the Kenner):
One thing is needful.—To 'give style' to one's character—a great and rare art! It is practised by those who survey all the strengths and weaknesses that their nature has to offer and then fit them into an artistic plan until each appears as art and reason and even weaknesses delight the eye. Here a great mass of second nature has been added; there a piece of first nature removed—both times through long practice and daily work at it. Here the ugly that could not be removed is concealed; there it is reinterpreted into sublimity. Much that is vague and resisted shaping has been saved and employed for distant views—it is supposed to beckon towards the remote and immense. In the end, when the work is complete, it becomes clear how it was the force of a single taste that ruled and shaped everything great and small—whether the taste was good or bad means less than one may think; it's enough that it was one taste! It will be the strong and domineering natures who experience their most exquisite pleasure under such coercion, in being bound by but also perfected under their own law; the passion of their tremendous will becomes less intense in the face of all stylized nature, all conquered and serving nature; even when they have palaces to build and gardens to design, they resist giving nature free rein. Conversely, it is the weak characters with no power over themselves who hate the constraint of style: they feel that if this bitterly evil compulsion were to be imposed on them, they would have to become commonplace under it—they become slaves as soon as they serve; they hate to serve. Such minds—and they may be of the first rank—are always out to shape or interpret their environment as free nature—wild, arbitrary, fantastic, disorderly, and surprising—and they are well advised to do so, because only thus do they please themselves! For one thing is needful: that a human being should attain satisfaction with himself—be it through this or that poetry or art; only then is a human being at all tolerable to behold! Whoever is dissatisfied with himself is continually prepared to avenge himself for this, and we others will be his victims if only by having to endure his sight. For the sight of something ugly makes one bad and gloomy.
Quære: what thing is needful?
If you said "to give style to one's character", you are in excellent company, so far as I can tell, among Nietzsche scholars who comment on the passage (wouldn't illustrative examples be nice here? Yep!); you are also wrong. What is needful is that one should attain satisfaction with himself. Some do that by giving style to their characters, others by giving style to their environments. (It is also common to pass over the parts dealing with weak characters as of little interest.)
I am thinking of—later—putting up a post on the theme Things That I Realized in the Course of Teaching Nietzsche. One is: positions and people whom I formerly thought highly of fell somewhat in my esteem as I devoted more close attention to them than I had previously. Another: many papers on Nietzsche on Topic X don't read as closely, or with as much of an eye to context, as one would perhaps have liked. (Millgram's papers—Millgram not taking that approach—are very refreshing in this regard.) Here I actually do have some examples! But they will be deferred until that post, I think. Instead I will point out the curiosity of Nehamas' failing to mention, when arguing against reading Nietzsche's talk of self-creation as holding "that to become what one is is to actualize all the capacities for which one is inherently suited", not mentioning (even to dismiss it as not Nietzsche's mature/final position) Human, All Too Human 263:
Talent.—In as highly developed a humanity as ours now is everyone acquires from nature access to many talents. Everyone possesses inborn talent, but few possess the degree of inborn and acquired toughness, en durance and energy actually to become a talent, that is to say to become what he is: which means to discharge it in works and actions.
I mean, it seems like it might just support that reading!