Open Minecraft and join a world or server
Craft or obtain a pie if you are using a mod that adds one
Hold the pie in your hand
Aim at the player, mob, or target you want to hit
Right-click or use the attack/use button to throw or use the pie, if the mod allows it
If you meant a ray as in a beam or line effect, use a command, mod, or datapack that adds ray attacks
If you meant a pie chart, use external tools or mods, since vanilla Minecraft does not have a pie ray feature
If you meant something else by “pie ray,” tell me the exact mod or item name