今天是很好(今天 is a noun and 很is an adverb 好 is an adjective, so we use the adverb 很 to modify the adjective 好 ，but In Chinese grammar the noun can be modified by the adjective directly ,it does not need the verb 是)

今天是很好。我在十点半起了床(the word 了 usually is put after the verb and in the end of one sentence to express the past perfect tense ,so this sentence can be express like this 我在十点半起床了and the Pronunciation of 了in this sentence is the Hanyu Pinyin Liao )。然后我跟我的父母吃了中饭（In Chinese ,it is not necessary for you to emphasize your own parents 我的父母，you just need to say 然后我跟父母吃了中饭 and in this sentence the word 了 ，you use correctly because in this sentence the word 了 is used to express the actual action that occurs and  the Pronunciation of 了in this sentence is the Hanyu Pinyin Le）。我们去(吃 in Chinese there is also the verb to modify the noun like the English have the lunch ,so it needs a word 吃 to modify 点心)了点心。我最喜欢点心。你有没有吃过点心？

在下午我用了电脑(in this sentence the word 在 is not necessary，it is not like English there is a preposition before the time noun like on the afternoon ,and the word 了 is not need in this sentence)看小电影。我看了一些OMG美语！如果你看OMG美语你的英文是(I know that your meaning is if you watch the OMG American English ,your English will be very good, so you can use the word 会 to express the meaning of your English will be very good in the future  )非常好！我希望我的中文是她的中文好！(I understand you meaning you hope your Chinese to be good as her ,but in Chinese you should express like this ,我希望我的中文和她的一样好)

没关系；现在我在咖啡厅做中文作业。

Jonathan Come on !