As you have used the base machine and the melting furnace, you'll start understanding that the machines in Blackvoxel will often require you to build some sequences of cubes as the input of the machines.
There is an automation made to help you to build sequences in automated way : the sequencer.
The sequencer let you to program a sequence in it's interface. Once programmed, the sequencer will take the matching cubes at the input sides, then it will output them in the exact order and quantities. This will make automated sequences for the melting furnace, the machines and muche more..
First, follow the sequencer's manufacturing instructions in this page of the game manual in order to build some sequencer. Note that when building some sequencers, you'll get also an "end" symbol and an "alignment voxel".
Now, put the sequencer you made on the ground in an empty area. Then, open the sequencer's interface with the middle button of your mouse (or the "V" key).
In the interface, you'll see four zones.
Now, your mission is over, we'll see in the next mission how to use the sequencer in a concrete example.