Uh, there are a few (well, lots of) different ways to say this, which one to use depends on the context. It would have helped if you had written some "situations", but I'll try anyway. 正解 can be used for "correct", eg. when someone gets the correct answer in a quiz. 正しい could be a better term for "right", it's not as limited as 正解. That's probably not what you're looking for though, "you're right" would be そう/そうね/そうだね when casually agreeing with someone. You can say 本当だ when you didn't know/expect that something was right. その通り can be used as a pretty strong "that's right". I could say リナさんの言うとおり if I think you're right about something. You could use http://eow.alc.co.jp to find phrases, just search in English. If you can't read the Japanese just paste it into http://www.rikai.com/ (that goes for this text too).

You're right. means 正解　せいかい？ 「正解」がよくつかいますね