I don't understand colons in Python

[dsplayer14]

Well, here is my code:

print "Welcome to the English to Pig Latin translator!"
original = raw_input("Please enter a word: ")
pyg = "ay"
if len(original) >= 1 and original.isalpha()
    word = original.lower()
    first = word[0]
        if word == a or e or i or o or u
        print "Your first letter is a vowel"
        else print "You'r first letter is a consonant"
        print
    print "So your word is " + original
else:
    print "No word detected."

As you can see there are no colons, even thought there should be. It is not a finished program yet and I am doing it for this site called http://codecademy.com I need help understanding colons in python...

[snippsat]

Colons(:) are basic and important in python.
Other languages use { } or other method to indicate/use a code block.
Python use indentation after colons(:) to indicate/use a code block.

word = 'hi'
if word == 'hi':
    print'Now this block get executed an word is equal to hi'
else:
    print'Now this block get executed an word is not equal to hi'

So it look like this.

print "Welcome to the English to Pig Latin translator!"
original = raw_input("Please enter a word: ")
pyg = "ay"
if len(original) >= 1 and original.isalpha():
    word = original.lower()
    first = word[0]
    #if word == a or e or i or o or u:
    if first in 'aeiou':
        print "Your first letter is a vowel"
    else:
        print "You'r first letter is a consonant"
        print "So your word is {}".format(original)
else:
    print "No word detected."

[TrustyTony]

Every time group of statements follows, that line ends in colon and the block is indented.

[dsplayer14]

Thanks for the explanation snippsat. Also thanks for correcting that line of code with the vowels, I shoulda known it couldn't have been that easy...