Connect the USB sound card to a free USB port on your computer.
Install the music software that you purchased. To do this, insert the CD that comes with the package into your computer's disc drive and follow the on screen instructions.
Use an XLR cable to connect the microphone to an XLR input on the sound card.
Connect your instrument -- guitar, keyboard etc -- to the sound card using a 1/4-inch jack lead.
Decide whether you wish to use headphones or speakers for playback. If using headphones, plug them into the headphone output jack on the sound card. If using speakers, connect the line level output on the sound card to your monitor speakers.
Open the downloaded music software, adjust your levels and select a channel for recording. You are now ready to record.