If you really want to add sugar, you would boil a cup or two of filtered/bottled water for 4-5 minutes, dissolve the sugar in it, cover with sanitized (sprayed w/ StarSan) foil and let it cool to 65* then very gently pour it in.
Why do you want to add sugar to an IPA? Trying to boost ABV? If you add a significant amount, you'll end up with a thinner, dry brew which may lack the needed maltiness to balance out the hop additions. Just be aware that you may be unhappy with the result.
Good Temp Control -----> Happy Yeast ------> Tasty Brew