Connecting two DC power supplies in series involves connecting the positive terminal of the first power supply to the negative terminal of the second power supply. This creates a "daisy chain" connection where the voltage of the two power supplies is added together.

The following are the steps to connect two DC power supplies in series:

1. Turn off both power supplies and unplug them from the wall to ensure safety.

2. Locate the positive and negative terminals of each power supply. The mark for the positive terminal is usually a plus sign or the word VCC, and the negative terminal is usually a minus sign or the word GND.

3. Connect the positive terminal of the first power supply to the negative terminal of the second power supply using a wire.

4. Connect the load (the device you need to power) to the positive terminal of the second power supply and the negative terminal of the first power supply.

5. Plug both power supplies back in and turn them on.

It is important to note that the voltage of the load should be equal to or higher than the sum of the voltage of both power supplies to prevent damage to the load or the power supplies. Also, the current rating of the load should be equal to or lower than the lowest current rating of both power supplies.

Only use power supplies from the same product series and with the same rated output current. The maximum load current should not exceed the smallest rated output current when selecting power supplies with different current ratings.

Also, it is essential to check the polarity of the power supplies before connecting since connecting them with opposite polarities could cause damage to the power supplies or the connected devices.