zypper is for the management of rpm packages that are built for the opensuse distribution. It doesn't let you do it with a source file. You can use a source tarball if you want, but you'll have to know how to compile it from source.
If you're not familiar with zypper, I would start with this article:
http://en.opensuse.org/SDB:Zypper_usage
To find thunderbird, you can use the search option.
Code:
# zypper search thunderbird
Loading repository data...
Reading installed packages...
S | Name | Summary | Type
--+----------------------------------------+------------------------+-----------
| MozillaThunderbird | The Stand-Alone Mozi-> | package
| MozillaThunderbird | The Stand-Alone Mozi-> | srcpackage
| MozillaThunderbird-buildsymbols | Breakpad buildsymbol-> | package
| MozillaThunderbird-devel | Mozilla Thunderbird -> | package
| MozillaThunderbird-translations-common | Common translations -> | package
| MozillaThunderbird-translations-other | Extra translations f-> | package
| tracker-miner-thunderbird | Tracker miner to ind-> | package
Installing thunderbird is simply accomplished by issuing
zypper install MozillaThunderbird.