Using the multi-tool in crimper mode (or a special crimping tool), apply pressure on the connector 'shank' where the wire was inserted.

The ridge that you achieve by crimping should look the same as the connector shown here on the green wire. Give the connector a gentle pull to confirm it is well connected to the wire (it should not slip off).

Repeat steps 10 and 11 for the remaining two wires requiring connectors.