You can explore our Vegetable Planting Calendar resource to determine what plants are best started this time of year, and herbs are also generally compact plants that can be put in now. (Some are perennial and might overwinter, but others, like basil, don't survive the cold, so will need replacing next year.) Since this is a fairly small raised bed, you can use both our Planting Vegetables in Containers, Growing Vegetables in Containers, and Soil to Fill Raised Beds pages for guidance about what materials to consider using and what to consider growing. If the bed doesn't receive at least 6-8 hours of direct summer sun in its location, that will limit what can be successfully grown (or it will at least reduce yields). For example, leafy greens and some herbs (parsley, chives, tarragon, sage, and basil) should do alright.

Miri