Double Ninth Festival (is it lao ren jie 老人节？）

Double Ninth Festival is a traditional Chinese Festival. I’m glad to introduce you to this festival.

In China, we celebrate it by climbing hills and going out with parents. In the other way, Another custom is that we also look after the old people/elderly in many ways. In To my mind, it is important for kids children ('kids' is a slang word, don't use it in writing) to respect senior/elderly people. We usually help them to do some housework, like washing clothes or sweeping the floor. It can make old people happy joy ('joy' is a noun). As far as I concerned, it is a typical way to help them and I will continue doing that in the future. I am fond of respecting/showing respect to old people. Above all, I hope everyone going on observes/celebrates/takes part in this traditional event.

The Double Ninth Festival is not only going on outings with relative, but also the symbol of helping and respecting old people.

Don't worry that there are a lot of changes (yellow and red), what you had written was not bad!