My problems is, that i need to copy and image from alfresco to a local folder, i supposed that i need to use the method read, Does Anyone know how i can do it?
Yes you are correct, you want to use the method read on the content web service.
This will give you a content object which contains a URL. This URL points to the download servlet and if requested will return the content you are after.
See ContentUtils.java in the web service client project for some helper methods to do this.