Skilling shards can be found while training skills. A player must be training a specific skill for each shard. For Example mine ore to find Mining Skilling Shards.
Cooking Shard Here is an example of combining a Cooking Skilling Shard. A player must gather all 4 unique pieces before capable of combining. With all 4 unique pieces click on any of them and select "Combine".
After Combining the shards they will become a single Cooking Full Skilling Shard. A player can repeat this process with any Skilling Shard fragments to create the full one. Adding pictures below or reference..