Have:
- All-New Invaders 1, 3
- Amazing Spider-Man 1
- Iron Man 23.NOW
Want:
- ComiXology gifts
- 100th Anniversary: Guardians of the Galaxy
- Captain Marvel 3-current
- New Avengers 13-15
- Original Sin: Hulk vs Iron Man 2, 3
You have to redeem the codes on Marvel's website, but once they are redeemed they immediately sync with a ComiXology account (provided the Marvel account you redeemed the code with is associated with the ComiXology account. It's probably simpler than how I'm making it sound, really). And yeah, that's exactly what you use to trade here (though since these codes last for about a year, some of the ones you have might be expired), simply post a list of the codes you have/want here and see how it works