Anchoring the sculpture pieces can be pretty straightforward. Once the concrete foundation is ready, use a hammerdrill to drill holes into the concrete. Install a piece of steel threaded rod thru the sculptures and projecting, say 6" below the bottom of the piece. Then you can epoxy glue a threaded rod into the hole.
For corrosion resistance, try to get stainless steel, or galvanized all-thread rod, perhaps 3/8" diameter, or larger.
The epoxy for use with concrete is readily available at construction supply houses. Pay attention to the manufacturer's instructions on the exact diameter drill bit to use for your size rod.
If you don't have a hammer drill, and bits, these can readily be rented at tool rental places.