The home goes to auction at a trustee sale. More then likely it will either be downtown or El Cajon but if you see the Notice of Trustee Sale then it will be stated. At the trustee sale the home will be available to be purchased by the public for cash. The opening bid will most likely be less then what the default amount is however it probably will not be known until the night before or the morning of the trustee sale.
If nobody purchases the home at auction then it will go back to the beneficiary, (the lender). How long it takes to go back to the market depends on many things. Since there are renters in the home then that will lengthen the process. If the renters are smart they can occupy the home for awhile before they are evicted. The lender will dispose of the home by hiring a disposition company. That company will have an asset manager who will hire a brokerage to list and sell the home. More then likely that brokerage will work on getting the tenants out and then doing whatever needs to be done to get the house on the market. It could take a few weeks, it could take a few months.