I have downloaded an image and i have selected the piece of it that i want to use as a texture in a background.
After create a new document and paste the selected piece, is there any way to use it as a texture? or should i save it and then use it as a texture?
Saving the texture as a file would be the most common method. Once saved, you can load the texture into a Fireworks document from within the Properties panel. Select the object to which you'll be applying the texture, and go to the Textures dropdown menu. Choose "Other…" at the bottom of the list and then browse for the file.