You will start at the Vanilla spawn which is located at the center of the world.
There are some basic starter items which you can claim with the /kit starter command.
You can claim land with a golden shovel by right-clicking two opposite corners.
Once you have received your starter kit, you can leave the spawn area and head out into the wild to find a place to settle. Make sure you claim your land to prevent anyone else from building on it or stealing your items.
Please make sure to read the server rules before starting your adventure.