Looks like a 1964-1965 Sears Spaceliner built by Murray. Missing the tank with light & horn, rear light, and front fender. Pedals & Seat are incorrect although your seat is probably more comfortable than an original. The reference thread on these is at:
http://thecabe.com/vbulletin/showthread.php?35629-The-Ultimate-Sears-Spaceliner-Reference
Yours is probably:
46911 (1964-65, 26", Deluxe chrome, Woman's, single speed, springer fork, tail light, horn)
Hope this helps & welcome to the CABE!!!!!!!!!!