I think the map is pretty decent for your first try. To answer your questions:
*To delete or get rid of an object or tile, simply right click (while you have what ever tile type selected in the palette)
*You can just do prnt screen, then copy it with CNTRL-V in paint or w/e program you have so you can just save as a PNG/JPG..
Also, don't forget that the borders of the map need the "edge" tiles.. If those aren't in place some noob can just go roaming around willy nilly lol. Overall, though, not bad I guess for your first map!:)
Sleep With One Eye Open