请帮我看下英语日记这么写行吗?

下面是我改的，你对比一下吧。
Today I'm very happy. After breakfast, I went to park. It's a sunny day, birds were singing, I was singing too. When I got to the park, I saw some girls playing games, so I joined them. We played very happy. Then I had lunch with my friends. We all had a good time. What a happy day!

首先，要用过去时，因为你写的是已经过去的事情。bird应该用复数birds。“both”应该改称“all”，both是指两个，你前面说和“friends”（复数，超过一个）吃饭，再加上你自己应该超过2个，所以用all。“what's a happy day！”应该为“What a happy day！”,这是“What a happy day it is！”的省略形式。感叹句要倒装。
最后，每一句话的开头度应该大写，每一个标点符号后面都应该空一格（引号除外）。

继续努力吧！

belbin改得不错。我加一点：
the birds were singing (不可能只有一只鸟）
we all had a good time

我给你改了改 时态的话要改成过去时，你自己改把
Today I'm very happy,after breakfast,I go to park.
It's a sunny day today,the bird is singing,I'm singing too.When I get to park,I see some girls playing games ,so I join them.We play very happily.Then I have lunch with my friends.We all have a good time.what's a hap