Stepping stones dilemma - Advice for laying stepping stones

[chuffed2bits]

Hi All,
Am an enthusiastic but inexperienced DIY er - I want to lay some 30cm diameter stepping stones in a courtyard that has a solid concrete base but having read the excellent advice pages am worried that I don't have a sub base to excavate! Is there a way I can lay the stones onto the slab that will prevent them from coming adrift?
Many thanks
Celia

[GB_Groundworks]

the concrete is your sub base, lay them on to the concrete with a good 3 or 4 sand to 1 cement mortar mix