I also bought three wooden shelf brackets for each shelf, small ones for the top shelf and larger ones for the bottom shelf. I got mine from Lowes but there are lots of options that come in different sizes on Amazon too. Examples are here, here and here.
I painted the brackets separately from the shelves.
After painting the shelves and wooden shelf brackets, I lined up the bottom shelf brackets perfectly and screwed them into the wall. I then used an apoxy glue along the top of each bracket and gently laid the wider shelf in place. I waited for the glue to set and repeated the process with the top shelf.
And viola! Our DIY shoe rack! For more on our entryway update, see the original post here.