Corrections in red.  Better variant in blue.

My first encounter with italki.com

I watched a YouTube channel, and I saw a link to italki.com, and became interested. I had never heard of this site before.

"I had never heard ......."  -- past perfect tense.

http://usefulenglish.ru/grammar/the-key-to-the-past-tenses

My first meeting with italki.com

I watched a youtube channel and i saw a link of italki.com and I got interested. I have never heard about this site before.