Have a Crush

How would you say that you have a crush on somebody in Japanese, I've looked on ALC.co.jp and there appears to be quite a few ways to say that you have a crush.

But what would the fluent Japanese speaker, who there are a few off on here use to say that they had a crush on somebody?

I took a look at ALC and all of them seem appropriate. It just depends on the context or character. ALC is very reliable but not detailed, that's all.
http://eow.alc.co.jp/Have+a+Crush+/UTF-8/

It's just I was talking to a friend and I was telling her that I had a crush on a certain girl using the （人）に熱をあげる and she didn't understand and asked if I meant 風邪

But yeah I used a different sentence from that site and she understood. Are they're any sites like ALC that contain sentences like that? I can say that ALC has really improved my Japanese.

Topic Creator (that's a better name), although it greatly depends on your preferences, in general I can't think of a free on-line dictionary that is better than ALC. But another way to look up examples is to simply put quotation marks on your phrase and search it on your favorite search engine. See?
http://www.google.co.jp/search?q=%E2%80%9D%E7%86%B1%E3%82%92...

Your friend probably either lacked vocabulary (as many younger Japanese people do), or since you mentioned the phrase out of the blue, she couldn't instantly figure out what you were trying to say (which of course, even happens among conversation between locals). I don't think that people would normally imagine having a cold when you're clearly adding "(name) ni" to "netsu o ageru".

But in reality, if speaking out of the blue, teenagers would typically say something like, "Ore/atashi (name) ga suki nanda yone." which is quite enough to get you through. And then you can start adding adjectives and slangs depending on how much you want to enphasize it.

Another thing might be is that this "[name] ni netsu wo ageru/agete iru" may be used more when talking about someone going crazy for someone else (observation) rather than talking about oneself. Or could have been just lack of vocabulary :)

BTW, I refer to it as ALC, too, but it's actually dictionary called "Eijiro," right?

I've always wondered about you. How are you so fluent in both languages? What is your native language?

I learned English in Europe where the commonly used expression (for what you call a crush) was "to fancy someone" so the first time I heard a US person say they had a crush on so and so,I thought that they had a car accident and actually crushed, squashed, ran over,the other person!