The Boss GT 10 is a guitar effects pedal, not a recording station. In order to record using a Boss GT 10 you will need to have some type of recording equipment with which to actually capture the sound that the pedal helps you create. The GT 10 is, however, a power effects processor that can greatly simplify recording your guitar. Although it is possible to run the Boss GT 10 through and amplifier and record in the traditional method using microphones, the GT 10 is designed to be ran directly into a digital recording workstation.
Get a recording program. If you have an Apple computer, Garageband (a fairly powerful recording program) is already loaded on it, if not, you will have to purchase a program such as Pro Tools or Cakewalk or download a free recording program like Audacity.
Plug your guitar into the input of the Boss GT 10 using a guitar cable. Run a cable from the Boss GT 10's output to your amplifier's input. Make sure everything is plugged in properly and turn on the amp and the Boss GT 10.
Experiment with the pedal until you find a guitar tone that you wish to record. The Boss GT 10 offers an almost endless supply of different guitar tones, so don't settle for a sound that isn't quite what you want.
Attach the Boss GT 10 your digital recording station. Depending on the type of equipment that you are using (type of computer, mixers or audio interfaces) you may do this with a variety of chords. The GT 10 unit has a USB out, a 1/8 inch digital out (good for running straight into a computer) and a 1/4 inch headphones jack, all of which can be used to run the sound into a computer.
Hit the record button on your recording program and play a couple of notes and chords to see if everything is working correctly. If you are getting no sound, make sure that you are using the proper input on your computer. A mic input will work if you cannot get any others to work. Adjust the volume using the GT 10's volume pedal until you get the right levels.
Record your guitar part. Once you have the first part recorded, you can go back and record more guitar parts over top of the original part.
Different types of recording programs have different specific controls, but the process of recording a guitar using an effects pedal such as a Boss GT 10 is fairly straight forward. Simply hit the record button and play your instrument. The GT 10's user manual can help you troubleshoot any problems you may have with the set-up of the pedal.