Go to Video Settings and set Smooth Lighting to OFF. This is the most common reason X-Ray packs look like solid black blocks.

Avoid .exe files; legitimate texture packs are always compressed folders or .zip files. How to Install the Pack in Eaglercraft

Ensure you aren't trying to use a 1.8.8 pack on a 1.5.2 server.

Since Eaglercraft runs in your browser, you don't need to access local AppData folders. Follow these steps: Launch your version of Eaglercraft. Go to from the main menu. Click on Resource Packs .

If the pack doesn't load, refresh your browser and clear the site data, then try re-uploading. A Note on Fair Play

The main issue with standard Minecraft texture packs in Eaglercraft is the way the browser handles transparency and custom JSON files. A "fixed" pack ensures that stone, dirt, and gravel become completely invisible while ores remain highlighted, without causing the "black screen" or "flicker" bugs common in unoptimized files. Where to Find Fixed X-Ray Packs