When you give someone an injection you use a syringe to put some liquid into them through a small needle.
The person in the picture is being vaccinated.
Inlaying is a decorative technique, where some of a surface is cut out and filled in with another material so that the surface of the inlay is the same height as the original surface. Usually the inlay material is brightly colored, a shiny metal, or a pretty material such as mother of pearl. The surface being inlaid is most commonly wood, and inlay work is commonly seen on furniture in some countries. Metal jewelry can be inlaid with gemstones or contrasting metal.
Someone is innocent if they have done nothing wrong.
The opposite of innocent is guilty.