You will need:
1. inside resource packs, create a new folder with the EXACT name you want your resource pack to be called.
2. Inside, make the following things- a png (it is what the resource pack's image looks like in the pack selection screen and can be whatever you want), a folder called 'assets', and a file called 'pack.mcmeta' in something like notepad.
3. in the pack.mcmeta file, put the following text:
all on the first line of the file. you can change the 'Pack description here.' part to whatever you want the description for the pack to be, but keep the speech marks. save this in the resource pack folder with your resource pack (if you know what I mean) as 'pack.mcmeta' EXACTLY (only without the quotes).
4. inside the assets folder you made, make a folder called 'minecraft'. in the minecraft folder that you just made, make the following folders for the sounds. you don't have to make all of them, just the ones where in the original assets folder the sounds you are replacing are found.
here is a full list:
5. to change a sound, you need to effectively mirror the sound's 'location' (file it's in) in the resource pack's assets minecraft folder. for example, if you wanted to change the record 13's song, you would
you can add textures, but this is for sounds.
hope this helped!
if it's complicated, let me know, and I'll try to explain it.
Oh and last note, if this is the wrong section, feel free to move it to the appropriate location. this IS a new section after all.