How to add custom device tree to build?

Hi,

I would like to addd a customized device tree to my cc6ulstarter build. i’ve attempted to follow https://www.digi.com/resources/documentation/digidocs/embedded/dey/2.4/cc6ul/yocto_t_add-new-custom-machine, have added the custom dtb line to the makefile but am getting stuck at adding a new custom layer to the Yocto build: On the above link under “Add new machine in custom Digi Embedded Yocto layer” it says the following: “You must copy the Linux kernel default configuration file to the meta-custom layer, as Yocto does not use the one included in the kernel tree.” but I see, there’s this file that came in when I cloned the meta-custom repo: https://github.com/digi-embedded/meta-custom/blob/ccimx6ul/custom/recipes-kernel/linux/linux-dey-4.1/custom/defconfig
I then created recipes-bsp/u-boot/u-boot-dey_v2017.03.bbappend and recipes-kernel/linux/linux-dey_4.9.bbappend after which I’m not so sure how to actually invoke bitbake now to compile this, bitbake core-image-base didn’t seem to build anything even though I’ve sourced it like: $ source /usr/local/dey-3.2/mkproject.sh -m meta-custom -p custom
What am I missing?