You can install any and all the packages that you have in you linux-Mint CD or DVD with the standard installers such as Adept or using the console with apt-get install, or if you have it in your cd/dvd with synaptic.
Let's assume that you want to install packages that are not in your cd/dvd, then you can get the packages from many sources and save it to add to you repositories, is they are ubuntu packages you just use the same installers mentioned above, if they are debian packages you can use Gdebi, and if they are other well known formats, then, you can use alien for the installation.
I am no expert and have hardly the need to go through all the configuration process myself I just use the available installers. Others may prefer - and know how to do it- to configure their packages for particular reasons: servers, developers, etc,
Hope it may help,
Note: I am beyond apologizing for my english, or should I say Â¨spanglishÂ¨ as much as saying okay for the occasional Â¨englispamÂ¨ that I read. I guess we are beyond that and enjoying ourselves nontheless...