Do you have some Java fern in that tank? I can't tell, but if you buried the rootstock, then that will kill it. I find the easiest way to attach it to wood is with an elastic band. Then when the roots grab the wood, you can cut the elastic off.

Is your betta very young? He looks a tiny bit thin.....

track how much I have spent...well, I've decided I am probably better off not knowing! lol.
Definitely better off not knowing!