Solaris use the System V standard packaging format.
Packages are installed with the pkgadd command.
Should you want to know more about it, have a look at the pkgadd, pkginfo, pkgmk, pkgparam, pkgproto, pkgtrans and pkgrm manual pages.
Finally, there is pkg-get
http://www.bolthole.com/solaris/pkg-get.html, a freeware wrapper "à la" apt-get, easing package installation by automatically managing dependancies.