I hope someone out there can help me. I bought a cactus and the guy in the shop didn't really know much about how to take care of it so a bit of advice regarding how often to water it and how much sun it should have would be much helpful.
Over the past few weeks, I have also noticed some brown patches (see attached photos). I'm not sure if it's normal or not or what I should do about it. It would be very grateful if someone could look at the photos and had any idea about what it is.
moderator's note: added a more descriptive title to topic
moderator's note: moved topic to more appropriate forum