Isn't that the question of the day? I really suck at this game. I don't know what I'm doing lol. I've fainted 3 times already from throwing seeds and I don't entirely know how the shipping system works. I'm going to have to look up a guide.
To avoid passing out, I usually save when I get low on stamina so I can reload if I overdo it. Also, you can eat at Raegar's restaurant to regain stamina, which I'd advise anyways because later on in the game you will unlock recipes from him for eating there (I think to get them all you have to buy like 130 meals, so best to start early). Also, once you buy the blueprint/build your kitchen, you can use crops to make your own meals if you like.
As for the shipping system, instead of a shipping bin this time around there are vendors. At the start you only have one, Silk Country, so unfortunately there will be spans of 3 days where you cannot sell anything. But later on once you unlock more (which you do by shipping lots of items) it will be easier because they will come on different days.
I'm not sure how far you are, but Veronica should show you where the Trade Depot is during the tutorial. All you have to do is go there on days when a vendor is present (use your calendar to check, if there is a festival make sure to press Y to check if a vender is still coming, took me a while to realize they could come on festival days, haha), and talk to the vender. Choose the first option, "Ship", and you can sell things from your inventory. You can also sell from your storage at home, just click the button for "Change" at the bottom (I believe it's Y or X, can't remember) and pick where you want to ship from.
And for everyone who is confused, don't worry, I've played most HM games and I was still left thinking, "What do I do now?" with this one. I think because the game has no real storyline it's a bit weird to start off. I went to bed early most nights because there seemed to be nothing left to do other than animals, crops, forage, repeat. But I'm at the end of Spring now and it's picking up a bit more. And a lot of things unlock in Summer and Fall, like more vendors, so it just takes a bit.
edit; Oh, and also seconding the fogu recommendation. That's the only other forum I'm really active on, even longer than I've been here. It's a great place to post questions, or just gather info from other's threads. The actual guide is still a work-in-progress, but more pages are being put up, and even now it has a lot of helpful info.