Yes, up next to File in the toolbar menu, go to Edit, then Undo. Also, if you want to delete something, click on it so it turns red, then hit Delete on your computer's keyboard. If you have any questions, come on over to my chatroom on dA, I am always there. [link]
or try using ctrl z to go back and ctrl x to delete a red highlighted object, ctrl A selects everything.... most functions can be done with the ctrl button and a letter key..the shortcuts are listed beside the actions in the edit menu
thank you so so much for the info, 1 question.....The first thing you create,comes on the forground,the second behind,and than the third ,etc. If I wish the third must on the forground,what must I do than????(sorry for my english)
Ok .. I think you can just make sure the third (or any object you want) is highlighted in red ( it should be red straight after you create it) and then use the REPOSITION tool ( a cube four places along the top in EDIT with arrows in each direction coming from it). I think that each item you create actually comes right on top of the other so they should all start in exactly the same place.. If you find you need to be exact then you can reposition using the co-ordinates in the A tab that pops up when you have an object highlighted in red.
I hope that helps .. note me or vicky if you need more help but Vicky is far better than me lol
Once you learn the buttons you should be ok, then just start adding things and moving them around to see what happens. Bryce is very big in Europe, you might be able to find something in your language somewhere.