Connect your microphone to the XLR to USB device using an XLR cable. XLR is the standard connection type for most microphone connections. An XLR connection has three prongs, arranged in a triangular formation. You can purchase XLR cables at any audio store and most electronics stores.
Plug the XLR to USB device into your computer's USB port. Confirm that it is detected as an input device. In Windows, check the audio devices under "Hardware and Sound Settings" in the Control Panel. In Mac OS X, check the input device under "Sound" in System Preferences. If the XLR to USB does not appear as a device, plug it in again or restart your computer.
Open your audio recording software.
Speak into the microphone to test its signal strength. Make sure that an input signal is visible on your audio software's level meters.
Adjust the level on your XLR to USB device, if there is a control to do so. Many XLR to USB devices have a dial for the gain of the signal, in order to amplify the audio before it reaches your computer. Set the gain dial as high as you wish for the specific project and leave it there. Any further level adjustment should take place on the computer.
Adjust the level of the incoming signal on your computer, once you have settled on a level for the device itself. In order to adjust the input level on your computer, you can access your audio settings through system preferences. Alternatively, if you are using audio software to process the microphone signal, you can adjust the level from within that program.