All of the guests at a witch wedding will be asked to form a circle.
Generally people stand throughout, but it's not a long ceremony. There is also no problem with individuals choosing to sit on a camping stool, if standing will cause physical hardship.
Speak with the High Priest and/or the High Priestess beforehand, in order to accommodate this.
As all are spread out, in a circle as large as there are people to create it, everyone has a perfect view of what's going on. The bride and groom will stand in the middle, along with the clergy officiating. That's where all the 'action' takes place.
Casting the circle will involve the officiant(s) raising an athame in the air. To the initiated, this will look precisely like a knife or dagger. But it's symbolic. They would no more use it as an actual weapon than you would. It will be used to outline a pentagram in the air.
This will happen at the altar, then at four points around the circle - east, south, west and north. You will hear them call upon gods and elementals to witness what happens here. At this point, please do feel free to ask your own deity (or saints, or angels, or djinns, or whatever else may protect you and yours) to equally watch over the circle.
But please don't do this negatively. Asking your own deity to disrupt the circle is not only disrespectful, but tantamount to cursing the marriage of the couple before you.
I tend to raise the circle within the group of people forming it. Technically, that means that they are the circle, or are standing just outside it. If the priest or priestess steps behind you all, then you're firmly inside the circle.
Once it's raised, then the rest may look very familiar. It's all about saying vows and asking people to witness those being spoken. Food and drink will be shared. It'll only be a mouthful - blessed by the bride and groom - as this again is quite symbolic.
The actual moment of marriage comes when the couple's hands are bound together. That is the handfasting. They will then leap over a broomstick. That seals the deal and they are now wed.
There will be a final pause, as the circle is taken down again. Then all are free to celebrate with a big party!