Здравствуйте, исправьте, пожалуйста, ошибки в сочинении (все очень плохо с периодически)

Здрасти, исправьте, пожалуйста, ошибки в сочинении (все очень плохо с периодически)
One of the most important lessons I have learned in life was when I did my school project. I began to make the presentation to this the day before the defense. It was half past one when I have finished. I pressed the save button, but, suddenly, my computer stopped working. I managed to fix it only by rebooting. The presentation has been deleted.
I felt myself very awful. Luckily, on the next day my mum agreed to help me. Together we мейд the presentation in one hour and I passed my project to the highest score.
Afterwards, I have undestood, that time is precious and that we shouldn't put off till tomorrow, what we can do today.