Doubleclick on the little speaker icon in your taskbar next to the clock to open the software mixer applet.

Locate the fader for "Mic" -- if it is not there, try the options menu to check the box fot showing Mic.

The Mic input is typically MUTED by default so that a new user won't get feedback from the speakers when they activate the Mic. Uncheck that and also you may have to revisit the fader a few times to adjust level so your guitar is at the right monitoring level along with the other tracks as you record.

NOTE: The Mic input jack is WRONG for what you are doing as it is electrically "too hot" and the wrong impedance. However, with careful adjustment of the Output volume on that guitar pedal (keep it LOW) you should be able to get started with recording like that.

Have Fun,

--Mac