From Admin panel, go to Catalog → Product. Edit product you want set is new product.
In the basic settings panel, Click Advanced Pricing link
Advanced Pricing panel:
Enter the number of the Special Price.
Assign the active time including Special Price From Date and Special Price To Date. You can type manually or click on Calendar icon to choose the relevant date.
From Admin panel, go to Catalog → Product. Edit product you want set is new product.
In the basic settings panel, Click Advanced Pricing link
Advanced Pricing panel: