Yeah... I was going to ask you that too... What those "applaud" and "smite" buttons are for ? If I click on applaud, what is going to happen ?
avast is going to transfer a nice bonus of $10,000 from your bank account to Technical's located on Cayman Islands.

Naaah, just kiddin'...

It's just the Karma thing you see in each user's profile. Each appluad means +1, each smite -1. So it's sort of popularity measure...
All i have to do is check in avast! or do i need to set my mozilla settings also?
If all your mail is currently being scanned and all you want now is to insert the avast text info to the footer of each message, then yes, all you have to do is change the settings in the Internet Mail provider in avast.
Anyway, what I'd like to say is that you might also consider that adding these 'signatures' to your mails can also be sort of nuisance for other parties (especially if you're sending e.g. to newsgroups (via SMTP) etc...). I mean, some AV programs do have turned on this feature by default (AVG etc.). but most computer professionals agree on the fact that it's in fact an unsolicited ad that is constantly flooding the Internet...
So it's up to you to make your choice...

Vlk