Hi Aymen, the corrections and additional info are in red:

Congrats to the Italki challenge winners !

A famous proverb says, ''A thousand miles trip begins with one step''. Also, "When there is a will there is a way.''

By the end of the italki challenge, I would like to greet your courage, your motivation and your determination.

I suppose that even a couple of hours studying a new language (new grammar and vocabulary) is difficult and sometimes frustrating but that's the real challenge!

It requires a lot of energy and reviewing the new stuffs learnt the new things your learnt (saying "learnt" by the way is more British English, Americans would say "learned" instead). Finally, I would like to say that the languages world world of languages is really a magical world since it allows many people around the world to meet, have common target language to learn and marvelous cultural background to share ! to share their cultures with one another. (I changed the last part for style, the world marvelous is a bit old and not commonly used at least in America).