Great that you want to take care of the birds. Always make sure that the entrance hole points south east in direction of the rising sun. Also make sure that the location of the nesting box is cat-safe. Experience has shown that a height from three to four meters is favourable. Install the box quite early because the birds look out for their breeding area quite early as well.
If you are interested in the breeding and would like to do some birdwatching, there are good bundles of cameras on the market. Just install the camera in the nesting box and wire it to your television, for example.
And a last tip: Clean out the nesting box as soon as the first breed has left. This way it is ready for the second breed.