I'm grateful

Hi.
Today I want to tell you about my experience on this website, I know there's much to learn but I've found valuable help...
Thanks for your corrections.

Regards...

Almost perfect -- I only changed "in" to "on." There's nothing wrong with using "much," although it is more common in affirmative statements to say "a lot of," and to use "much" in questions and negative statements, as well as in reference to periods of time.

I'm grateful

Hi.
Today I want to tell you about my experience in with this website, I know there's much a lot to learn but I've found valuable help...
Thanks for your corrections.

Regards...

I'm grateful
Hi.
Today I want to tell you about my experience with this website, I know there's  a lot to learn but I've found valuable help...
Thanks for your corrections.

Regards...