I want to dedicate poetry to the world, but I have no culture.

The next sentence "I wanted to dedicate my poems to the world, but I have no culture" can be "Brothers are really talented, as I saw Li Taibai in those days".

This sentence means that I originally wanted to express my feelings and thoughts with poetry and dedicate them to the world, but because I have no culture, I can't write good poems, so I am helpless. On the other hand, my brother is very talented, and his poetry level makes people feel as white as before. This is a kind of self-mockery and praise for the brother's talent. Through this sentence, we can feel the speaker's humility to his cultural level and admiration for his brother's talent.