[LAU] Interfacing an electric guitar

Hello all, Just got an electric guitar. First time. Now putting on a new set of strings. Got a 1/4" wire and a passive direct box that's already used for a Wavedrum. Got also a small guitar amp with an headphone out jack, as an option. The audio card is a M-Audio 1010LT. Can I simply take the 1/4" wire from the passive direct box and connect it to the guitar ? I believe there's a guitar processing app out there called something like rackarrack or such. Does this work through jackd as in doing the audio routing using qjackctl ? Alternatively if I want the amp's sound and processing, I can simply use the amp's headphone out, although I'd like to try the computer based only interface and processing. Cheers.