how can i create my account on MIT App Inventor website ?
Urm...... how are you creating this topic then????
Actually, this might be confusing to people as there isn't an "open account" thing in our website. Maybe, I'll talk with the team about this
i created account on community of MIT App Inventor, not in MIT App Inventor website itself
yeah, because i've seen people asking about getting a certificate by submitting a Request for Certificate from within their accounts on MIT App Inventor account, by going into the Projects option in the account
I don't know anything about the certificate but, when you are on the main page of the website you press "create apps" and then it will ask you what Google account you want to use and then sign you in
Sorry, only just realized when that was posted 
you probably figured it out already