Welcome to the hobby! Theres lots of info available on fishlore. If you have any specific questions feel free to ask and theres lots of people (including myself) who would love to chime in with any help we can offer. Saltwater IMO is a lot more involved and requires more research but can be very rewarding if done right. Not to scare you but just aware of the cost associated with salty tanks. I also have a 15 gal nano which im trying to turn into a reef tank and I have invested over $700 including inverts/fish/coral.