Why can't i transfer tunes i bought to smilebox

I don't know what the technical reason might be not knowing about what formats Smilebox accepts or what procedure might be necessary for uploading, though it appears you need to have purchased a Premium Design or be a subscriber to their "Club Smilebox" to be able to add your own music.

But uploading commercial recordings to share with others is both illegal - it's a violation of copyright law to share tracks outside of your household - and a violation of the terms of sale of the iTunes Store which state that all items you purchase are for your personal use only. If you want to share tracks with anyone else, you must have a license to do so, and the record companies not surprisiningly want money for such licenses.

So unless this creation will be something that you will not make available to others, particularly not on a web site somewhere, you cannot use music purchased from the iTunes Store (nor any other download store nor CDs). Look into one of the many sources where you can purchase royalty-free music, or purchase it from Smilebox; they have licensed music you can use.

Regards.