First make sure your pot has enough drainage holes. Next you'll need to cover the holes with something that will let water out, but keep your soil in. For this metal container, I've used a heavy plastic bag with lots of small holes punched in it. You can also use plastic window screening or coffee filters to cover the holes. An even better solution is Better than Rocks plastic mesh. Also, keep in mind that if you live in a hot climate, the metal can get really hot - hot enough to burn you or your plants, so be careful.
Next add enough soil to your container so that your plants will sit an inch or two from the top of your pot. This will make it easier to water them.
Take your plants out of their nursery pots and if the roots are visible and packed together, gently pull them apart.
Place your plants in your container and make sure to give them some room. In most container gardens I cram plants close together, but in this case, some plants, particularly basil, needs space for air circulation.
Once you have placed your plants add soil, making sure to fill in the spaces between the plants, and pat it down gently.
When you are finished water generously - making sure to add water until it runs out the bottom of the container.