Home made Sauna

Hello everyone, I just bought a house and because the previous owners used walkers the whole thing is wheel chair accessible. So what that means for me is I have 2 showers. I am into saunas and cold plunges, so I want to convert the smaller shower into a sauna. I am curious if anyone has done something similar or has any insight with how they would approach this? Any information is appreciated. It currently has some sort of rock looking walls with silicone sealing it. Do i need to worry about pressure and vapors? Will the silicone getting hot give me cancer? How should I approach the electrical install part? Thanks in advance. (I don’t want to hire anyone for the sake of cost, but I will most likely end up having someone come do the wiring so i know it wont burn my house down. )