Spring festival is on（on改成in,只有具体到天的时候才用on） January or February .People in China celebrates（celebrate.people是个复数） it.
Spring Festival is（这里加个the.最高级前要加定冠词the） most important festival in China.People celebrate （这里加个it.celebrate是及物动词后面不能没宾语吧）in different ways.We usually have a big dinner on Spring Festival’s Eve.Next day ,we do a lot of activities .We watch the lion dance and the fireworks.Usually we visit our relatives and friends.And we can eat lots of Chinese food.They are very nice.
Children wear new clothes.And children （不觉得跟前面一个children重复用很别扭吗,最好改成they）always get some red packets from their parents,relatives and older friends.
Everyone is very happy at Spring Festival.
改完的如下：
Spring festival is in January or February .People in China celebrate it.
Spring Festival is the most important festival in China.People celebrate it in different ways.We usually have a big dinner on Spring Festival’s Eve.Next day ,we do a lot of activities .We watch the lion dance and the fireworks.Usually we visit our relatives and friends.And we can eat lots of Chinese food.They are very nice.
Children wear new clothes.And they always get some red packets from their parents,relatives and older friends.
Everyone is very happy at Spring Festival.