Newly bought clothes, I feel that I have no confidence in wearing them in the street and at school, and I am afraid that others will laugh. . What to do?

I'm too self-abased, I care about what others think of me, and I'm sure I rarely change my hair style and I haven't done anything unconventional. Although I may be cheerful on the surface and feel inferior inside, I might as well change myself more, and I will get used to it if people around me say I don't look good.