Hey you guys, do you know that today is earth day?

Hey you guys, do you know that today is earth day?

1. What i did it on today: (You have two options for this sentence)

a. Normal: What I did today:

b. Emphasize Earth Day:  What I did for Earth Day:

c. You could also write "What I did for it today"...but it sounds awkward.

2. I just turn off the light switch when i went out for send a post box to my friend jiyeon
(I packed had been storing my skateboard and her wallet at my home, and had promised give a skate board to her when My little bone(which bone? hand/foot/finger/neck?) was broken) (Because you have different reasons for sending the two objects, you should not put them in the same sentence particle)

a.  You can put the location and the reason: to my mailbox to send a package to my friend Jiyeon.

b. The location can be assumed so you could just put the reason: to send a package to my friend Jiyeon

3. I want to be aware person that which thing is nice for our in the world
I just wanted to do worth thing.

You can say this different ways:

a. I want to be aware of my impact on the earth and do worthwhile things for it.

b. I want to be a person aware of things I can do for the world.  I just want to do worthwhile things.

But it is too small I have not done enough.

I have to do more big thing at least in the next years (next year/ following years/ the future) (next has a nuance of only one)

Have a good day!

Good work.  Let me know if you have any questions.

Good job! There are mistakes, but I can understand almost everything that you wrote. There are several ways to write this without mistakes, but here is one possibility:

Hey you guys, do you know that today is earth day?
What I did today:

I just turned off the lights when I went out to mail a package to my friend Jiyeon. (...not clear what you mean by "her wallet" and "my little bone"...)

I want people to be aware of the nice things in our world.

I just wanted to do something worthwhile.

But it is too small.

I want to do something bigger, at least in the coming years.
Have a good day!