Do you just have the 1 tree so far?
Once you get your restoration up I think 1 level, drag your builders over to that wooden thing and have them fix it.
Anytime it starts to rain, put someone on the empty side. They will go up and get a seed.
It will make up to 3 trees, but they run out fast.
Later on, I've read you have to make a specail potion to kill the sharks. Still working on that one. Something about once you get things up, you'll get a potion bottle. Use that and 2 orchids to make the potion to poison the sharks, then you can fish.
Also the chief can grant food every 24 hours and look for mushrooms constantly.