First Journal

you could write; 我第一天的日记

大家好， 我是simon， 我 住在Taiwan。今年开始写中文自己学习自学中文。

我是simon， I am Simon
我叫simon, my name is Simon
Those sentences are similar mean, which introduces you to others in Chinese. Don't have a huge difference.

Taiwan
Chinese [ simple] ; 台湾

自学中文 more simple and make sense
you words I translate in English. you can feel it where the mistake.
I write Chinese, I study by myself.
I suggest；今年我自学中文
I study Chinese by myself.

我 要写和说比较好

I don't understand this one.
maybe you can write what you want to say in English to me.

大家好， 我是simon， 我 住在Taiwan。我今年开始写中文自己学习自学中文。

我 要写和说比较好想做到能写会说。