This might be a dumb question but I will ask anywho. If I make a structure or something big in a single-player creative mode, can I download or get that structure into our server? I know it can't be done, do I know correctly?
You have to rebuild it on the server. You can do it by hand or use a Program called Schematica that makes a template of where to put the blocks... http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/1285818-schematica
Just to add on to this, if you do use schematica, DO NOT use the printer function to auto place the blocks. This is illegal and will get you banned.
Makes sense. I know it would but I thought if I had the enough materials, I might get it automatically hehehe. But yea like others said, I will look into that Schematica and NOT use printer.
As a rule of thumb with mods: if they give you an (unfair) advantage over other players then it's usually best not to use them unless they're explicitly mentioned on the mods wiki page. So if a mod does something automatically (like fishing, placing blocks, sorting inventory) then you should always think about whether it's allowed or not. Just to be safe. Sometimes it is, and sometimes it's not