How do I put all of my data on the SD card on my 3DS?

I'm wanting to trade in my 3DS towards the purchase of a 3DS XL,and I'm not sure how to get all of my data(games,saves,ect.) onto the SD card I have in my 3DS now..I have info and downloaded games I don't want to lose..I know this is a TOTALLY noob question,but if I could get some help without bashing me or telling me like "duh!" or something,I'd really appreciate it :D

You need 'em both to make a successful data transfer. Don't trade or sell your old system before you have made the transfer.

I'm wanting to trade in my 3DS towards the purchase of a 3DS XL,and I'm not sure how to get all of my data(games,saves,ect.) onto the SD card I have in my 3DS now..I have info and downloaded games I don't want to lose..I know this is a TOTALLY noob question,but if I could get some help without bashing me or telling me like "duh!" or something,I'd really appreciate it :D

GameGoddess32