This is probably a situation that we have all been through. Being the new guy, whether it's an intern or a regular employee is tricky. It always involves the cold-start problem, since you are in a new place, with new people, new technologies, new methodologies.
I totally understand the anxiety of not knowing something and wanting to get to know it perfectly, so that you soon become productive.
Having questions is totally natural. And you can be certain that your colleagues know that you do and will have questions. They've also been at your position at some point, right? And believe me, they HAD to get some help from somewhere.
The tricky part is that not everyone is available at all times, to answer any of the questions you might have. My usual trick when going through code or documents, is keeping notes of things that are not immediately clear, and arranging a couple of short meetings per day, to discuss them with my seniors.
Before asking a questions, it's always a good idea to make a small 'research' about it, try to get as many information and hints as possible. Sites like StackOverflow are gold. You might even get the exact answer you are looking for. Your colleagues will appreciate the effort, and will be more happy to help you.
Try hard, study hard, be curious, and ask questions. Remember, everyone has been in your position, and everyone eventually survived :)