The video above explains exactly how to make a texture pack for the latest version of Minecraft Bedrock Edition
How to make a Minecraft Bedrock texture pack (resource pack):
1) Get the template pack
Follow this link to download the official template texture pack for Minecraft Bedrock Edition. Make sure you download the highest release with the green "latest" tag. Once you've downloaded it you want to right click on zip file and select the "extract all" option, If the option doesn't show install a program called 7zip.You should be left with a file folder and can delete the zip file if you want. Enter the folder and delete everything exept the "resource_pack" folder and its contents, then continue into the remaining folder and delete everything exept the "textures" folder and its contents.
2) Texturing
You should now have access to all of Minecraft Bedrock Edition's texture files (inside of the folder called "textures". Here you will find folders with names and corresponding texture files. Note for example that the "blocks" folder contains the texture of every block in Minecraft. Simply choose any of the image files and edit them to your liking, get as creative as you want! For editing you can use any image editor you want, however, I recommend Paint.net.
3) The manifest.json file
Once you've completed your texturing you can head back to the location where you can see the "textures" folder. Here you want to right click, choose "new" and then select "text document". Once you've done that enter the document with a text editor of your liking (I recommend Notepad++). Then you want to paste the manifest.json file, the contents of which can be found Here. Under the "name" and "description" tags of the file you've just pasted you can fill in a name and description for your pack if you want to. To be able to import your pack you need to replace the two exising UUIDs under the "uuid" tags. To generate new UUIDs go here. Replace both of the existing UUIDs with unique newly generated UUIDs. Once that's been done you can save the file, close it, and rename it to manifest.json it is very important that the file type changes to json. If this doesn't work for you, visit the txt-json converter.
4) Preparing the import
Optionally you can now add a pack icon to your texture pack. Place the file you want in the same location as the manifest.json file and make sure its name is "pack_icon.png". Important: it HAS to be a png file. Once you've done that select the folder THAT CONTAINS the textures folder (and your manifest file & icon) and right click. Then choose the option to "compress to zip". Similarly to ealier you might need to use 7zip to perform this action depending on your operating system. Now you're left with a zip file that you can rename to whatever you want to call your pack. When renaming, you want to replace the .zip at the end of the file name with .mcpack. If this doesn't work work you, try visiting the zip-mcpack converter.
6) Importing
Congrats! You've finished your texture pack. You can now simply double click on your pack and I'll import right into minecraft bedrock edition, if it doesn't, right click, choose "open with" and then select "Minecraft" :)) Encountering an issue while importing your pack? Visit the pack fixer.
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Minecraft Texture Pack Video Tutorial