As for Shinbon and First Bon, there are various differences depending on the region and denomination, so it cannot be said unequivocally.
The ways of offering offerings and festivals also differ depending on the region and denomination.
If it's just for the family, I don't think any special preparations are necessary, but since this is the first Obon festival, I think it's okay to offer something that your husband likes or something in season that you'd like to feed your husband, and just put their hands together.
However, speaking of the Buddhist meaning of Obon, I think the focus will be on things such as offering food and alms, so please make lots of offerings not only to the Buddha at your place, but if possible, to all the hotokesama in this world.
There is also a region where Obon is a homecoming day for Hoke.
There's no such thing as having to do this, but if there's anything you absolutely have to prepare, it would be a group of smiles between you and your two sons.
Please make Obon your husband happy.