I have a site with PHP & my gallery by coppermine (in coppermine folder)
How can view random image in other pages, such az contact.php (in root)
That's what we call "content syndication" (displaying content taken from coppermine on non-coppermine driven pages). There's a whole sub-board (http://forum.coppermine-gallery.net/index.php/board,57.0.html) of mods that offer solutions for that. The dev team recommends cpmFetch (http://forum.coppermine-gallery.net/index.php/topic,35450.0.html). Has been asked and answered very often already... ::)
Not related to bridging - moving accordingly.