How do i apply a photo to wood??

https://www.wikihow.com/Adhere-Paper-to-Wood

https://www.wikihow.com/Transfer-an-Image-to-Wood-Using-Gesso

https://www.wikihow.com/Mod-Podge-Paper-to-Wood

https://www.wikihow.com/Decoupage

Assuming that the photo i printed on good photo stock paper you should be able to mount it like any other photo. Most mounting boards are cardboard anyway. But a couple of thoughts for best results.

Align the photo where you want it and mast of around the photo n the wood with blue painters tape to mark where the photo will be placed. Do not tape the photo done, just tape right up to the edge. this way if you are using a spray mount glue you can spray the wood and the back of the photo for a better bond if that is what the instructions call for. Even if you are just placing glue directly on the back of the photo, masking the wood will help you place the photo right the first time.

Once you hand set the photo, remove the tape and roller out the photo to set it. If you have a piece of glass that can cover the photo temporarily use that with books, if not that is ok, but stack books on top to compress the photo until everything sets.

You can also use Modge Podge or other craft glues to mount the photos as long as the photo has sufficiently dried and the inks are set. If you are worried about inks running on the photo, use a clear spray varnish to set the photo and give it a day to dry. You can also use Modge Podge or a Polyurethane over the whole piece later to seal everything together. If you plan of doing a top coat, do a test piece with a scrap piece of wood to make sure the photos won't bubble up. Some glues react poorly to each other and bubble.

One really neat trick I discovered is that you can use Inkjet T-Shirt Transfers to pint and iron onto wood as well. The Dark Shirt ones will give you different results from the regular light shirt transfers.

I have a tutorial over here - https://happydealhappyday.com/photo-transfer-wood-rustic-antique-style/

You need matte gel medium and the image printed on a laser printer (NOT inkjet!)