(this only works if you have singleplayer commands or if your a mod or up in a multiplayer server)
/gamemode (name here) (1 for creative 0 for survival)
ex: /gamemode blabla34 1 creative
or
to switch from survival to creative and back just do:
/gm
Chat with our AI personalities
If you are the server owner (or can get the owners to change game mode or just yours) you can switch it to creative mode in the server conf file or by command in game by and op. otherwise a server in survival mode is staying in survival mode.
You can't.
Command blocks are only obtained by creative or mods. You must be in creative mode in order to successfully type a command into the command block, otherwise you will be prompted to be in creative mode.
Download the mode or change the play mode to creative.
A game called Eden it is a game like minecraft except you play like in creative mode in minecraft