Thunderbird for Mint

[Doug]

I see by the email that a Mint question is welcome here--that's good, 
since I got no answer from librelist, which I believe is their mailing 
list. So:

I have just opened up Mint KDE with the intention of using it--it has 
been installed for a while now--and I realize that Thunderbird does not 
seem to be readily available.
I have downloaded the compacted file from the Internet and decrypted it, 
but now I don't know what to do next. It is a whole slew of files. How 
do I go about installing this?

Please do not suggest that I use some other mail system. I have been 
committed to Thunderbird for several years after being badly burned by a 
Linux mail system and I
do not intend to let that happen again.

Thanx for your assistance--doug