Their language is not for the newbie
I'll give it another shot; I often need to hear things several different ways before I understand. And it's always helpful if the examples used are the same ones I'm trying to work with.
You need Crystal Lighthouse (CL) runes for the rune wheel. You understand anytime that broken shards bar in the CL rune wheel window is full with 10 broken shards, it will forge one CL rune that will automatically insert in the rune wheel and is guaranteed not to break. You've done that. How to get 10 broken shards to fill that bar again:
You haven't built the Tome of Secrets (ToS) so I'll use that AW as the example. Since it's an AW unlocked early on, you should have quite a few runes for it. Open the rune wheel window of the ToS and begin inserting the runes into its rune wheel. Some will break and will add 1 broken shard to the broken shards bar. Do this until that bar is full (10 broken shards). Close the ToS rune wheel window. Open the CL rune wheel window. Since all AW's share the same broken shards bar, that bar is now also full in the CL rune wheel window. Forge rune; it will auto insert in the wheel, guaranteed not to break. You still need a rune for the CL to finish the wheel. Return to ToS rune wheel window and repeat steps you did before.
*What if you end up with the ToS rune wheel complete, but still need more CL runes?*
Build the ToS. Once it's finished, sell it off*. You get the ToS back in your AW inventory, but lose the runes you put in before building, so empty rune wheel again. Repeat all steps above until you've completed the rune wheel in the CL.
*Edit to add: you can't just cancel construction, you have to sell the AW. If you cancel construction, you get the ToS back in your inventory but the rune wheel is full and ready to upgrade. That won't help you break runes to make broken shards.
Also: I found it helpful to never think of the term 'shards' when referring to runes and never use the word 'rune' when referring to broken shards. Yes, I know the game does; they named them rune shards and broken rune shards. It just sounds confusing to me. My brain is way happier with 'runes' and 'broken shards' and I use my mental eraser to ignore the rune/shards when found in the 'wrong' location, lol!