You can use 4, 5 or 6 panels. They should all be oriented into the same direction (Sout East, South or South West. If the attack angle is very low (10..15%) half of the panels can face toward WEST, the other half towards East. This will spread the energy harvesting more evenly over the day.
Connect the panels in series. Connect a long red wire to the positive plug of the first panel and a long black cable to the negative plug of the last panel.
The long wires will lead to the inverter which will usually sit near your fuse box.
When attaching MC4 connectors to the ends of the black and the red wire make sure that you attach a female connector to one end of each wire and a male connector to its other end.
Use a proper crimping tool: 
Be careful, once you have connected the panels there will be a voltage of 120 Volts or more at the open ends of the cables.