Set the mixer in a place where the rear inputs and outputs are unobstructed and you can reach all the equipment you need to with the cables you have.
Connect the mixer to the power supply.
Connect the two XLR or RCA cables to the master outputs on the mixer and run them to your chosen output device. Depending on your particular setup, this might be a pair of studio monitors, a home hi-fi, or the speakers of a PA system. Connect the left output to the left input, and the right output to the right input.
Connect any instruments or other input devices to the input sockets at the top of each channel strip. Turn down the volume sliders to zero for each connected channel. Label the square at the bottom of each strip with a dry-erase marker.
Any outboard effects, such as compressors, reverb units or similar, should be connected to the mixer's auxiliary bus, allowing the effect to be blended with the signal of any channel. Connect the "Aux Send" socket to the input of the effects device and the "Aux Return" socket to the device's output. The effect can then be applied to any channel by turning up the "Aux Send" control on the strip.