除了让学外语的人写故事和文章，在这里读者也可以发现修改其他人的句子和帮助别人。

在这里 is kind of cumbersome, you could delete it. 修改 instead of 发现.

你有这个机会因为“Messenger”。

I suppose you mean that you could chat with others thanks to Messenger. You could translate it into something like “因为有Messenger这个软件，你在LangCorrect上可以跟别人聊天”. OR, you could simply say “你可以在LangCorrect上用Messenger和别人聊天”. The latter one would be much more natural to me.

另一个其他的优点是这个网站有许多人。

我之前写了故事在Journaly写了故事，但是在那里帮别人的人真少。

哈哈哈我就是看了你的故事 然后从journaly过来的

因为学习中文时有点儿奇怪困难，所以这个问题更大。

I suppose you mean it's a bit difficult to learn Chinese. We don't usually use strange to describe language learning, right?

什么颜色都好看——吸引眼睛球。

很不幸地，这些几个星期我几乎每个天需要做天都要考试，所以我写得越来越少。

In Chinese, we would start the sentence with "很不幸，" or "不幸的是，" instead of "不幸地，”.

但是，星期四后来我就没有考试啊了！

然之后，我能更会有更多的时间用LangCorrect，这会让我更开心——我再说强调一遍，LangCorrect真的不错。

1. 之后 means from then on. 然后 means then/later, which feels more immediate than 之后.
2. I know after correction the sentence is longer and the expression is more complex, but simply translating 'I can use ... more' into “我更能用...” is incorrect. In Chinese, we would say I would have more time to (= 我会有更多的时间...), or we would say I would have more chances to (= 我会有更多的机会... )
3. 我再强调一遍 (= I emphasize/reinforce)
OR you could say 我再重复一遍 (= I repeat), depending on what you really mean.