Python Caesar Cipher

I need to create a code for Caesar Cipher. I need to use a for loop to examine every character of text, find shifted character using ALPHABET, key, and String functions, and add this to the end of "encipheredTextSoFar". Need help, not finished but I'm stuck.

EDIT:

I finally got it and this is my final code:

def circularShift(text, key):
    text = text.upper()
    cipher = ""
    for letter in text:
        shifted = ord(letter) + key
        if shifted < 65:
            shifted += 26
        if shifted > 90:
            shifted -= 26
        cipher += chr(shifted)
    return cipher

print (circularShift("MOLLOY", 3))
print (circularShift("PROORB", -3))

Python source code:

# setting status default value to 'y'
status = 'y'

# started a while loop until status will change from 'y' to 'n'
while status == 'y':
    # requesting which word to cipher.
    word = str(raw_input("Word: "))
    # how many position to shift each letter
    shift = int(input("Shift: "))
    # added new line to have pretty output
    print

    # declaring cipher variable to be of type list
    cipher = list()
    # iterating trough each character in word
    for item in word:
        # translanting each characher in word to new character
        # and appending it to cipher list
        cipher.append(chr(ord(item)+shift))

    # printing word
    print word
    # printing ciphered word
    print ''.join(cipher)

    print
    # do We need to cipher another word? yes or no?
    status = raw_input("Repeat? [y|n]: ")
    print    

Output:

>>> 
Word: HelLo
Shift: 1

HelLo
IfmMp

Repeat? [y|n]: y

Word: AbCdEF
Shift: 2

AbCdEF
CdEfGH

Repeat? [y|n]: y

Word: abc
Shift: -1

abc
`ab

Repeat? [y|n]: y

Word: 456GHh
Shift: -2

456GHh
234EFf

Repeat? [y|n]: n

>>>