A 48/38/28 seems a little on the large size for a full suspension trail bike. But if that's what you wanted then fine. The more normal size for trail bikes is 44/32/22. The set you got sounds more suitable for a cyclocross bike.

The front derailleur should be fine but it will need to be moved up on the seat tube slightly to work with the new setup and then play with the final cage angle and cable adjustments a bit. There are also limit screws on the derailleur that will need to be adjsuted to suit the new crankset. Also you'll require a new chain since your big ring is so much bigger than the old ring that you would end up jamming things up if you try to move to a big to big gearing combination.

As for how to set things up go to www.parktool.com and click on the parts of the bike you're interested in learning about.