Some good advice on this recent same topic thread
My question to you would be what indoor trainer are you using and does it allow for you to fit all types of regular bike saddles?
IMO almost everyone new to cycling is going to struggle to cycle for an hour in the early stages. Even after 20 minutes constantly seated, which you generally are indoors, I would expect some discomfort initially. Try and set yourself a target of say 1 minute out of the saddle every 5-10 minutes to give some pressure relief.