I'm new to bonsai, I bought a green island ficus as my first tree and it went from green leaves and quite happy looking to brown curled leaves. I watered it when the soil looked dry but I don't know what happened , please help!

Hi

I am sure I dont need to tell you this but it looks dead/on it's death bed . A ficus is an evergreen tree so this shouldnt happen. As for how it died i can't really tell by the low quality image. It could have been a fungal infection maybe or some sort of pest. Also it depends where you live, ficus tree's arnt good with frost. I live in the uk and it's currently realy cold so I move my trees from the window every night and put them back in the morning. All this information is easly availabe tho and it's all about observation and trying to prevent/deal with problems as soon as you notice them. There can be many different things that kill off a tree.

Personally I would by a new tree, feel free to try and save it but it looks dead to me.

Next time you buy a tree read up on it,look how other people take care of theirs.

I figured it was dead/ dieing, which is unfortunate, do you think there is a way to revive it? Also I live in Canada so it's getting cold now too but I chose the warmest room with the best sun exposure. I am very new to this and I have books and have done research but I guess I just screwed up this time

Looks like you forgot to water it and/or it was on the heating and it dried out.
If it is still alive, keeping the substrate moist without drowning it should bring it back. But.. That is assuming you have some idea of taking care of plants. I suspect you will not succeed resuing it yourself.

Well I guess I'll give it a try, and I'll just have to learn more about plant care!

My first tree was a fukien tea tree, there easy to take care of in my opinion. If you still intrested just keep going its just a learning curve. I am currently trying to grow some tree's from cuttings and it's not easy

I am certainly going to continue learning, I have a juniper which is probably a more suitable tree for where I live anyways, and good luck with your bonsai experience!