At this point, you can leave your birdhouse gourd as is, au natural, or you can get creative and paint it. Even if you want to leave it natural, I'd suggest a few coats of a spray on varnish, to protect it from the elements.
There are just two more steps before we get to painting. First, we need to poke wire through the 2 top holes. Hopefully you've made the holes large enough to maneuver the wire through. If not, it's not to late to drill them a bit larger. Once through, twist the end together securely. You can cover the ends with plastic tape, to keep them from jabbing you. I like to wrap a section of rubber hose over that part of the wire, to protect me and the tree I'll be hanging the gourd from.
Next, we need to glue on the perch. Rim the hole with a good amount of wood glue, then twist the dowel into the hole so that approximately 1/4" is inside the gourd.
You may need to brace the dowel on something as it dries, to get it at a perpendicular position to the doorway. Allow to dry, at least overnight.
Finally - it's time to paint. I'm going for the colors that will complement the flowers nearby. I've found hanging the gourds and spray painting is the easiest way for me to get good coverage. I'm doing that here by suspending a broom handle across 2 saw horses.
Apply 2-3 coats of paint and let the birdhouses dry. Then apply 2 coats of varnish as a sealer. Again, I prefer the spray varnish because I get an even coverage without dripping.