Hi all,
I noticed a lot of people having trouble figuring out the commands, so here is a quick summary.

All items have a unique internal item ID (II ID) and a internal projectile ID etc. ect. which you can refer to in the /give command.

For example:
/give 4347
Gives you the Gray Zapinator. Just google the II ID and it should work.

P.S.
Some comments also mentioned not knowing where to type the commands. All comments should be typed in the in-game chat (i.e. the enter key)