For convenience, assuming that there is still a mortgage on the house that you want to rent out, the first step is to make an appointment with the bank or mortgage provider. They will eventually have to give permission to you to rent the property. The money they have borrowed you is still in the home. On the other hand, banks do want to receive their interest every month and so they will consider whether and under which conditions the renting out of your house is possible.

When there is no mortgage on the house, you are simply free to do what you want and renting is no problem at all.