Nic, pine shavings are little bits of pine wood shaved off a log. There are no pine needles at all. It is just as though you took your jack knife and peeled some thin wood pieces off a stick. They are sort of small and many are a bit curly. I buy them at the feed store, compressed into a big, rectangular bag. I plop a half bag onto the floor and in no time, the chickens have put it all over the floor by scratching while they look for yummies which might be on the floor. Does that help? What you do not want is cedar shavings, something you often find in regular pet stores for other types of caged animals.
Then, you just leave them on the floor for the chickens to walk on. Their poop dries out quickly, the moisture drawn out by the fine wood shavings. Some people just add more shavings over time, letting the floor get deeper and deeper and then shovel it all out once in awhile to replace with blond new shavings. This is called the deep litter method.