No, you do not need to download. You never have to download things for iD L if you're trying to get happy symbols.
HERE are what the seed packets look like, posted by binary. You can find them at the TamaDepa. Plant the seeds and wait till the next morning, then go outside and you will get an item. It might not be the item you wanted, so you should buy the seeds again and plant them.
I think there may be a way to get an item usually grown from seeds from one of the shops in the park, (maybe TamaMarket?) and skip the seed-planting process. Not completely sure on that one, though. I'd stick with growing seeds.