Skins packs can be used to personalise your appearance in the game. Teams will often have their own teamskin which they wear, you will need these installed to see the new textures, other people will not see your custom skins unless they have your skins installed on their computer. There is no need to install a skin on a Server, although a server can specify a custom skin as the defaults if they want.
Note: You can use any Tribes 2 skins for Legends, with varying aesthetic results. Just rename the Tribes 2 skins as follows:
some_tribes_2_skin.hmale.png → some_tribes_2_skin.heavy.png
some_tribes_2_skin.lmale.png → some_tribes_2_skin.light.png
Then place the some_tribes_2_skin.heavy.png and some_tribes_2_skin.light.png files in your \Legends\legends\data\shapes\player\male folder. You can use any of the other skin files too, like a lfemale.png, instead of the lmale.png or hmale.png. SEE “External Links for Tribes 2 Skins” section below on this page for links to Tribes 2 skins.
Note: .vl2 files are just a form of .zip. On Windows, untick the “Hide extensions for known file types” option in your folder options (under the View tab), and then just change the .vl2 suffix to .zip, and then extract the contents to see the skins.