Cemetery of Ash, Firelink Shrine bonfire
From the main bonfire, head up the stairs to the left and go outside, here there is a tree you can run up then jump across to the adjacent roof. Head down the rooftop and in through the doorway on your right
In here, go to the middle of the rafters, head left to find the Estus Shard
Please Note ~ If you are unable to make the jump from the tree, come back to Firelink Shrine and purchase the Tower Key from the Shrine Maiden for 20,000 souls, allowing you to ascend the Tower where you can drop off of the bridge on to the rooftop then follow the steps above