You'll be paying for expenses involved with the auction, advertising, etc..
Usually, you can have the auction at your house or, another location.
You can display the items in the house or, outside. But, if you put it outside be ready for a rainy day.
You will pay the auctioneer to move the items to the location, unless you want to do it yourself.
Normally, the items are advertised in flyers, papers and online. If you're selling the house, vehicles, etc., you may want to have an 'open house' or, by appointment only to allow potential buyers to look the items over before the sale.
I wouldn't sell the 'big stuff' or antiques separately from the auction. You need things like that to attract the bidders.
The box lots, furniture and other things are usually put out the morning of the sale and everyone can look before the auctions begins.
We've had a couple auctions. The nice thing is, at the end of the day everything (just about) is gone.
The downside is, you may or may not get what you wanted for your items. That's a chance you take.
Talk to a couple auctioneers before you decide.
Good luck which ever route you take.
It's much easier and quicker than CL or yard sales.