Hi and welcome to the forum. You will find this a great place to get all sorts of information about your tree. Take the time to read the posts as most beginner questions have been asked (and answered) many times!
I purchased this bonsai about an hour ago from a local garden centre and was extremely dissapointed when I read that these type of bonsai are the hardest to keep alive.
I found this a little interesting as you said you just found out this type of bonsai was hard to keep alive and then you followed with...
Firstly I don't know what species it is,
Sounds a little contradictory to me. How do you know it's hard to keep alive if you don't even know what it is?
Not trying to give you a hard time here...just thought it was kind of funny when I first read your post.
Your new tree looks exactly like my Chinese Elm and I'm pretty sure that's what you have. As far as I know it's a pretty easy tree to maintain. I bought one last fall. It has wintered in my garage and I'm waiting for the weather to warm a bit more before bringing it back outside.
Perhaps you were told this tree is hard to keep alive INSIDE?? That may be a problem as this tree may not do well if you plan to keep it inside. Keep in mind the vast majority of Bonsai must be kept outside where they adhere to the natural cycle of life.
I'm sure many other members will add to this post with advice. As I said before, look around and most of your questions will be answered.
Good luck with your new tree. I'm sure everything will work out just fine for you!