well, Grey Wolf Star, i have to say that ur pinyin passage really gimme the works and baffles me alot. better to use some simple chinese wods to express what u wanna say. so that's my "decoded" guesswork and hope it'll b helped.

ni hǎo, wǒ shì Hannah = Hello, i'm Hannah.
better to say "wǒ jiào Hannah"(我叫Hannah) natively. jiào means "named..."

wǒ shì 16 suì. = i'm 16.
it's alright to say "i AM 16" but in chinese, the predicate shì(am) is always dropped out.

wǒ shì yí hàn wèi wǒ bú kè yòng tú Zhōng guó xiě zuò = i'm so sorry but i can't use chinese to write
is that right? if so, the right pinyins r "wǒ shì(hěn) yí hàn wèi wǒ bú kè(néng) yòng tú zhōng guó(wén) xiě zuò" and into chinese "我很遗憾我不能用中文写作"

dàn shì wǒ shì yòng tú yī gè xiàn shàng cí diǎn = but i could use online dictionaries (to help me)
bingo? the corrected pinyins r "dàn shì wǒ shì(néng) yòng tú yī gè xiàn shàng cí diǎn", into chinese "但是我能用线上词典"

Wǒ bào yǒu qià qià kāi dòng xué wèn Zhōng guó bìng wù bào yǒu cún qǔ zhì mǒu wù bǐ róng xǔ wǒ rèn wǒ shì yòng tú duì le cuò cí
my! sweetie, r u speaking klingon? ))) gimme more details or write them by simple words, okay?

and btw, my personal suggestion, i mean, u'd better add ur english means as the so that more people could give u detailed corrections. anyway, easy does it and good luck, mademoiselle )))

First notebook entry: Introducing myself

Ni hǎo, wǒ shì Hannah. Wǒ 16 suì. Wǒ hén yí hàn yin wèi wǒ haí bù huì yòng Zhōng wén xiě zuò,  wǒ yòng yī gè xiàn shàng cí diǎn. Wǒ gāng gāng kāi shí xué Zhōng wén, bìng cún qǔ zì mǔ, zhè ké yi ràng wǒ míng baí wǒ shi fǒu yòng duì le cí.

It's a little difficult to understand, I've tried but I am not sure whether my translation is correct. Be free to correct if i made mistakes. :)

Hi, i'm Hannah, i'm sixteen years old. I'm so sorry bacause i can't use Chinese to write, but i use a online dictionary. I just  start learning Chinese and collecting letters.  It is important for me to understand if my use of words is correct.

Em...It's  a little hard to understand  its meaning ...Maybe I really understand u..If I don't really understand ur meaning,just sorry...If u work hard,u will speak Chinese soon..

恩，明白你写的是什么意思有一点难。也许我正确地理解了你的意思。如果你的意思我理解错了，那就不好意思了...如果你努力学中文，你不久就会学好中文....（These sentences r just translation of sentences I said just now...）

First notebook entry: Introducing myself

Ni hǎo, wǒ shì Hannah. Wǒ shì 16 suì. Wǒ shì yí hàn wèi wǒ bú kè yòng tú(U shouldn't say like that.U should say Wǒ duì wǒ bù néng yòng zhōng wén xiě zuò biǎo shì yí hàn) Zhōng guó （Chinese is diffrent from China in Chinese.u should say Zhōng Wén ）xiě zuò, dàn shì wǒ shì yòng tú yī gè xiàn shàng cí diǎn(zài xìan cí diǎn).

Wǒ bào yǒu qià qià kāi dòng xué wèn Zhōng guó bìng wù bào yǒu cún qǔ zhì mǒu wù bǐ róng xǔ wǒ rèn wǒ shì yòng tú duì le cuò cí. （I'm really sorry about I really can't understand u these words.I hope that u can speak Chinese well soon.）
你好，我是汉娜。我十六岁了。我很遗憾我不可以用中文写作。但是我使用一个在线词典。
I am also open to helping anyone wanting to learn english, and again because I'm not sure how what I wrote in Pinyin above turned out, apologize if what I wrote makes no sense whatsoever. :/

First notebook entry: Introducing myself

Ni hǎo, wǒ shì Hannah. Wǒ shì , 16 suì. Wǒ (hěn) yí hàn wèi wǒ bú (néng) yòng tú Zhōng (wén) xiě zuò, dàn shì wǒ shì yòng tú yī gè xiàn shàng cí diǎn. Wǒ bào yǒu qià qià kāi dòng xué wèn Zhōng guó bìng wù bào yǒu cún qǔ zhì mǒu wù bǐ róng xǔ wǒ rèn wǒ shì yòng tú duì le cuò cí.

I really can't understand the blue words.

First of all,I have to say you have a deep understanding about Pinyin.I remember when I first attended the elementary school,Pinyin was my first lesson.So it is a right choice for you to master Pinyin in the first place.I know it is hard for you guys to pronouce some of them.However,believe me,you will get over that!Also,If there are some mistakes in my sentences,I'll be glad if you point them out for me.Thanx~