- あなた は ひゃく ぶ う か?
Do you think you'll get a full score?
Full score: 満点（まんてん）
Do you think ~? : （あなたは）～と思（おも）いますか？
you'll get a full score : 満点（まんてん）をとる
あなたは満点をとると思いますか？
（あなたは まんてんを とる と おもいますか？）
This is too complicated structure for a beginner.
You should stick to a simple, basic sentence at this stage, such as "will you get a full score?"
- その は いつも おこるない。
That would never happen!
その cannot be used on its own - it must be placed before noun, to express "that xxx".
"That" alone should be それ
いつも : always
never : ぜったい／けっして～ない
起（おこ）る＋ない＝おこらない (you should learn verb conjugation first.)
それはけっしておこらない。
- だが, なして。
Nevertheless, you have to try.
Nevertheless : それでも
have to ～: ～なくてはならない、ねばならない
try : やってみる、ためす
それでも、やってみなくてはならない
それでも、やらなくてはならない
なして: I assume you picked up the word なす (to do) and try the conjugation of te-form (なして). But なす in the sense of "to do" is rarely used in daily conversation, it is usually used in a very formal writing.
Another word なして is a dialect meaning "why".
- よし。 いってきます。
Yeah, yeah. See you later.
よし is often used as "OK" "all right".
いってきます is a greeting to say when you're leaving home for somewhere, when you're expected to be back later.
There's no equivalent phrase in English, people often translate it as "good by".
See you later is またね, あとでね.
のち is another very formal sounding meaning "after" or "later".
You do not use it on its own, except in weather forecast;
晴（は）れのち曇（くも）り
fine, later cloudy
Later... (evening)
If this is a kind of stage direction (or in the drama, etc.), in Japanese
しばらくして (after a while)
夜になって (now in the evening)
sort of phrase is used but I cannot think of equivalent to "later" in this context. (Maybe it's only me, though.)
- こんばんは。
Hi.
- こんばんは。
Hi.
こんばんは is good evening.
It is OK to translate it as "hi" but to make it sound lighter as the same level as "hi" I would use やあ (if it is between friends and the speakers are male.)
- じゃ, どう でした か?
So how did it go?
じゃ: same as じゃあ, which is contracted form of では.
In this context it does not really fit - maybe you can say それじゃ（あ）.
どうでしたか is OK for "how did it go" though it sounds a bit too formal in your sentences.
- みち. ボく は あす に みいだす。
I won't know until tomorrow.
みち? I assume you mean 未知（みち）, which means "unkonwn" but it sounds far too formal as if formal writing.
Anyway, you cannot use it for "I don7t know".
I won't know ：わかりません or しりません (Here わかりません is better)
until tomorrow あすまで
みいだす（見出す） means "to find out".
Again it sounds too formal and rigid in this context.
へえ？ can be translated into various forms, like "oh, really?" "aha?" but anyway in this context if you use へえ？ it sounds as if you do not really agree or you are doubtful or scornful towards the one you're talking to.
Sorry I cannot understand the meaning/connotation of "Okay?" here either.
- は。 ぼく は ち に はしるべし。
Yeah. I have to hurry home.
は sounds like "huh!".
If it meant to be yeah, then it is うん.
うん is an informal form of はい(=yes).
- 窶堋ｾ窶堋｢窶堋ｶ窶堙･窶堋､窶堙? 窶堙懌?堋ｽ窶堙仰。
Alright, bye.
- だいじょうぶ, またね。
Alright, bye.
いってきます is wrong unless you're leaving home.
Recommendation:
Tae Kim's Japanese guide to Japanese grammar
Learn Japanese | Tae Kim's Guide to Learning Japanese