I'll show you specifically how to make hot cross buns and croissants but once you know the basics you can make anything.
Step 1: Making salt dough
I just got roughly the same amount of flour and salt and added water until it went doughy, but if you want to do things properly then just google a salt dough recipe.
To make everything in the first photo I only used the amount of salt dough you see in my hand here.
I cooked my salt dough on the lowest oven setting - less than Gas Mark 1 - and the smaller pieces only needed about 15 minutes, the larger ones I left in for 30 minutes.
You'll be able to tell when they're done as they should go white and hard and not be squishy in the middle.