There are multiple keyboard layouts, but I'll assume you're using the inscript layout, which is the most common. Vowels are located on the left side, and input by pressing shift + (key). For example, Shift + E will type आ. Aspirated consonants are located on the right side, and also input by pressing shift + (key). For example, Shift + H will type फ. This picture should hopefully help: https://en.wikipedia.org/wiki/File:Devanagari_INSCRIPT_Keyboard.JPG

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