If you typed yes in the prompt box, you should have received a warm greeting before seeing the rest of the page. If you typed something else, you shouldn't have received any greeting at all.

Here's the the heart of the script:

var monkey_love = prompt("Do you love the monkey?","Type yes or no");
if (monkey_love == "yes")
{
alert("Welcome! I'm so glad you came! Please, read on!");
}

Note that the condition is two equal signs. This is one of those things that everyone messes up initially. If you put one equal sign instead of two, you're telling JavaScript that monkey_love should equal "yes" instead of testing whether or not it actually does equal "yes." Luckily, most browsers look for this sort of mistake and will warn you about it when you try to run your script. However, it's best not to make the mistake in the first place.

Other typical conditions are:

(variable_1 > variable_2) is true if variable_1 is greater than variable_2
(variable_1 < variable_2) is true if variable_1 is less than variable_2
(variable_2 <= variable_2) is true if variable_1 is less than or equal to variable_2
(variable_1 != variable_2) is true if variable_1 does not equal variable_2

Two ways to make your conditions fancier:

If you want two things to be true before running the statements in the curly brackets, you can do this:

if ((age < 21) && (drinking_alcohol == "yes"))
{
document.writeln("Hey! You're too young to drink here!");
}

Notice the two ampersands. That's how you say "and" in JavaScript. Notice also that the whole clause, including the two sub-parts and the ampersands must be enclosed in parentheses.

If you want either one of two things to be true before running the statements in the curly brackets, do this:

if ((variable_1 == "bananas") || (variable_1 == "JavaScript"))
{
document.writeln("The monkey is happy because it has " + variable_1);
}