Make small holes for plant roots in your soil with a stick, then position your seedlings. Cover the roots with a little soil. If the neck of your container is narrow, you can use two long sticks pinched together chopstick style to position your plants. Add enough water to dampen the soil. Punch small holes in the lid.
Air can get in, but most of the water gets recycled in the container rather than evaporating away.
Add water occasionally if your terrarium gets dry.