You have already started. Now keep the dream alive.
You will need to get yourself a Marriage Licence. For more information on doing this and to apply online: Get a Marriage Licence
This will take a few days and the Licence will expire within 3 months so just be aware of your timing.
You will need to arrange a venue. When deciding on a venue you will need to make sure that you are allowed to use that space. If its a privately owned place check with the owner. Or if its a public space, like a park, you will need to gain authority from your local council.
Its also wise to have a back-up venue sorted just in case.
You will need to have 2 eligible people attend the ceremony as witnesses.
And, of course, you will need to have a Marriage Celebrant.
If you need my help with any of this, just let me know.