Basically, you have to decide what you want - and then be consistant.
For nighttime (which it sounds like you didn't have a problem) - you basically just keep putting them back in the bed over and over, not talking to them (except the first time you put them back, where you say something like "Bedtime" or "sleep time".) and not touching them anymore than you need to (ie, no hugs, etc.) You kind of need to keep an eye on them, without them knowing you are. Our bookshelf is right beside their bedroom door, so I take a long time to pick out a book the first couple of nights... lol.
For my oldest, the first night took about 90 mins to 2 hours of constantly putting him back in bed (very tiring for me!) - then the 2nd night was about 45 min, the 3rd night was about 15 min, and after than it was maybe 1 or 2 attempts to get out of bed. My 2nd was quicker. My 3rd (at 18 months, the youngest I've done this) has hardly gotten out of bed, but I think she is uncertain of the process to get out of bed.... so I suspect once she has more confidence at it, I will need to do the process.
For naps, you need to decide what is acceptable to you. If you want them to stay in bed, you need to do the same thing as at nighttime. For me, I changed the wording to "Quiet time" and if they were playing fairly quietly in the bedroom, that was fine. Occasionally they didn't sleep. My 3rd is having her quiet time in her playpen (And is rarely sleeping) because all 3 share the bedroom - and there is a bunkbed in there, and she is interested in climbing the ladder. She is fine if the other kids are in there - but I'm not having her in there alone.
btw - I generally only do the switch when it is safer to switch than to keep the crib. For my oldest, he was climbing out of the playpen. He hadn't climbed out of the crib yet, but it was a matter of time. He climbed the playpen at 19 months, but we switched the bed on his 2nd birthday. My 2nd was climbing over the babygate! She was about 20 months. I've switched the 3rd out early because there are 2 different safety recalls on her crib, both of which it is recommended to stop using the crib until you have the "repair" kits.