New cider maker - couple of questions

So I pressed a load of apples (50kg, 3 different types of eaters, with a small percentage of cookers thrown in) yesterday and I checked the alcohol potential of the juice and I was only getting a reading of 5%. I would have expected this to be higher.
I've checked the Hydrometer and it is fine - have I done something wrong, or is this normal and what can/should I do to raise the alcohol potential of the cider?

what was the reading?

Stop looking at the alcohol potential scale. While its somewhat valid in cider making (only if you plan to ferment to dryness), its really made for wine making. You should look at the Specific Gravity scale. Take a reading before fermentation, then one afterwards. There are forumlas on the net that will help you calculate your ABV with the two readings.

The 5% range sounds about right for apple juice. Apples, unlike grapes have a lot more water. I'm not the most experienced, but I'd guess you would be hard pressed (no pun intended) to yeild more than 6.5% from just apple juice. That would be with some seriously sugary apples. If you want more alcohol, you will have to add sugar. I recommend adding only enough sugar to get your Specific Gravity to around 1.065. Anything more than that will dry the cider out too much and take away the apple quality.

Cool, that was what I wanted to know. So roughly how much sugar should I be adding to raise the potential?