Due to the complexity of the Legends Mod, the installation process requires a few additional steps to ensure you have safely and successfully installed the mod.
Step 1: Make sure you are NOT using a preexisting world that had ANY mods on it, or was loaded in a version higher than 1.7.10 of Minecraft, before the Legends Mod was installed. If you load the mod on any preexisting modded worlds you are almost guaranteed world corruption. This is due to the required block ids already being taken by pre-existing blocks, since each world assigns it dynamically. Note, worlds using versions before the 2.0 Beta will also not work with anything higher due to the rewrite in the Revision Update.
Step 2: Download the 1Legends-Mod.jar and place it in your mods folder (like you would with any other mod). However, do NOT get rid of the '1' in front of the file name. The Legends Mod MUST LOAD FIRST in order to secure the proper block ids. Make sure there is nothing above the Legends Mod's placement in your mods folder.
Step 3: Download the maps.zip and unzip it. This should give you a folder called "maps". Place this folder inside the "legends" folder in your ".minecraft". If there is not one already generated (if you've not loaded up the mod before) then simply create a new folder in your .minecraft and call it "legends". This is the same folder guild information is stored in, for reference. The map installation is pretty similar to installing any other Minecraft world EXCEPT it goes into the "legends" folder in your .minecraft, NOT the "saves" folder. Always make sure you update your maps folder every time you download a new version of the mod!
Installing the mod and maps on the server is almost identical to singleplayer. The only difference is the "legends" folder will be with all your other server's folders (ie. mods, saves, etc) instead of in your .minecraft.