If the pack isn't appearing in your menu, follow these steps: , and hit enter. Navigate to .minecraft > resourcepacks Drop your X-Ray file here. In Minecraft, go to Options > Resource Packs , move the X-Ray pack to the right-hand column, and click 4. Common Fixes for "Black Screens"
Because you are looking through "solid" blocks, the game engine doesn't calculate light for those areas correctly. Using a "FullBright" mod or texture pack alongside the X-ray pack is highly recommended to see clearly in the dark. xray texture pack 188 work