How to get this yellow color from being in my tank?

The yellow color is more than likely from something called “tannins”. This is leached out by the driftwood in the tank, and can also leach out from soil if used in the tank as well. It does not mean that the driftwood is toxic at, it’s just a common thing and why the water near boggy areas is always dark black/yellow (due to all of the wood leaching out tannins like this).

A common way that people get rid of this from the start is to do big water changes, and then boil the driftwood for 10-15mins. That makes a vast majority of the tannins release right away compared to slowly over time. If you don’t want to boil it (or it’s too big to boil, not a good shape to) you can always add in a bag of Seachem Purgien to your tank and it will absorb all of the tannins until it needs to be recharged (bleached, and then rinsed with a ton of water).

Maybe people may recommend doing water changes, but this will resolve the current color (it will come back again in a few days).