ばか！バカ！　馬鹿ー月！

Is there a windows app, or a machine translator, where one can enter a Japanese sentence with Kanji in them and get it translated into pure Hiragana? I often see subtexts in Japanese with Hiragana above the Kanji, to make it easier for kids to read the text I assume, since kids have to learn Kana before learning Kanji. I have found a Windows app that will show Kanji with a specific trait in them, and you can give them more traits to narrow down the search, so 2-tail and B would produce 院 - 陸 - 険 - 陵. But this a tedious way to translate Kanji, so I am hoping for something a bit easier. I also know that a Kanji can be written with Hiragana in a variety of ways, but that part I quite frankly don't understand yet.

You probably already found one, but http://nihongo.j-talk.com/ is excellent for doing this.

Try http://jisho.org. You can enter English, Romaji or Japanese, or you can find the Kanji with radicals. Best site I've found.

You should try the Rikai-chan extension for Firefox (also available on Chrome) : https://kitagawa-keiko.org/misc/Rikaichan/
I use it daily and it really is helpful when you have to translate some sentences or when you browse a website ^^