Very good! Your grammar is quite strong. Many of the corrections are for typos and punctuation, with some suggestions for style.
What memory from your childhood is particularly vivid in your mind?
There is one childhood memory that I can easily remember, even though it was 13 years ago.I remember it as if it were yesterday when I was ready to attend the first day to kindergarten. I was very nervous and scared. My mother was very happy, because *for her it was like seeing her daughter growing up and ready to confront a new challenge. The morning was very **long, I could not stop thinking about being separated from my mother, toys, and friends, ***for lots of hours.
*Many words, but do they really add to the meaning? How about because she was seeing?
**In English this is called a comma splice. Clauses must not be separated only by a comma unless there is also a conjunction. A semicolon or colon will do. I suggest a colon: ...very long: for many hours, I... . The semicolon introduces an explanation. Note also the way "long" and "for many hours" fit together.
*** lots of hours is not very good. A "lot" is a set of many items sold wholesale, like a box containing cans of sauce from which the buyer picks one or two. "Lots of" is appropriate for physical objects or for abstract nouns that are otherwise uncountable: lots of cans, lots of juice, lots of love. Hours is neither; it's better to say for many hours. For a better style I suggest moving the phrase to the start of the clause, as above.
I realized that I was not the only one crying in the classroom and *get even more scared. I was mad and sad at the same time, because she let go of me. The teacher stared introducing **herself,she sounded very sweet and made all of us ***put attention to her because she was also funny. It was almost time, ****my mum walked me to the door of the classroom, but I could not hold it more, and *****stared crying, ******and running like crazy in a big hug, I felt and *****stared screaming that I *******do not wanted to stay there. But any of her advices change my thoughts.
*wrong tense sequence. Should be past tense.
**another comma splice. Here use a semi-colon herself; (why?)
***idiom. to pay attention.
****here there is another comma splice, but you are narrating events one after the other (which you were not in the other cases -- do you see why?), and so the comma is acceptable.
***** type? to start crying.
******This is a little garbled. Do you mean ...started crying, running around like crazy holding her in a hug. I actually started screaming... ?
*******I want, I do not want. I wanted, I did not want.
*The first thing we played was following a song, it was **a great fun because I made lots of ***friends, After this moment I didnít miss my mother anymore and wanted to stay there playing ****for lots of hours.
* A little garbled again. Watch the comma splices! Perhaps After we sang a song, the teacher let us play. It...
**"Fun" is an abstract noun. Should not use the indefinite article. ...was great fun
***Comma is a typo? Use .
****Poor idiom again. But you have already put "for many hours" above. Perhaps for a long time or for as long as I could.
In conclusion, the first day of kindergarten is my favorite childhood memory.