I've found few sites that have good information on how to cast spells with the cards. Probably because it's not one of the foremost uses for Tarot. And since Tarot is not magic in the way that wiccans and other pagans may practice it, perhaps some taroists avoid using the cards for spells in order to avoid the stigma that magic sometimes tends to receive.
But one thing remains certain - just as it's best to create your own spells with your own incantations and use of magical ingredients, it's best to create your own spells with tarot. You might go to a site online with tarot spells - there's a few of them around - but it remains that those spells were custom made for the ones who created them, and therefore not the best that can be created for you.
As long as you have an understanding of the cards, then you have the capability to cast your own spells with them. If, for example, you would like to mend a broken relationship, you might take two cards - one representing yourself, the other representing your lover, and cross both cards with the Strength card. Lay the cards out on an altar, surround them with candles or incense, whatever is suitable to the spell that you are casting. I'm no expert on spell ingredients.