To exchange resources firstly open the magic wheel (the one in the green square).
Choose the Exchange ritual the one in the middle
After that, you have to choose what to exchange for what.
By default, it will be souls to gold, love, fame, or notoriety.
If you wish to make acquire souls press the arrow in the blue square and reverse it.
When you decide what resource you want to get or spend press the buttons on the bottom (any of the 4).
Here you can choose the amount and “Trasmutate” to exchange.
You can also on the left corner switch the resources.
Ex: form soul into love, to love into souls.