Add in 1/4 cup bottled lemon juice (it's important you use bottled and that you use it all to make this jelly safe for canning) and 3T powdered pectin. Let the mix boil. Now, the recipe I jotted down on a napkin called for 3 cups of sugar. That sounds insane to me, but if you enjoy sugar shock, go for it. I used about 1 3/4 cup of sugar, stirred it in until it melted, and let it get to a hard boil and stay there for a minute (you have to let it get hot enough to reach the temp where pectin gels). Now, it can be a risk, messing with sugar in these recipes because the pectin and sugar react to one another to make the jelly set. So you have to use some. Taste it and see if it's sweet enough for you as you go. Keep a saucer in the freezer. When the mix has boiled for a minute, put a dab on the cold plate. If, after about 10-15 seconds, it gels up, you're good to go.
Make sure you've sterilized your jars in a boiling water bath and softened your lids (remember, you can only use the flat lid part ONCE to process a jar and make it shelf stable. Discard after one use). Pour into your jars, wipe the rims, lid them up, and process in a boiling water bath for five minutes. If you don't want to process in a water bath, just make the jelly and keep it in the fridge.
**Remember, it's really important to do some research about canning if you want to produce jars you can keep in the pantry rather than in the fridge. Botulism is some serious nasty. I haven't provided a basic run-down of Canning 101 here because there are links to several good resources for this on my website page. PLEASE don't can ANYTHING until you've educated yourself.**