Hi, Thank you writing to the Dell Community Forum.  The easiest way to add wireless option to your Desktop computer would be by using a USB Wifi Adapter. Linksys, Netgear, D-Link are few companies which provide USB Wifi Adapters. Please check for a Windows 10 compatible USB Wifi adapter to work with your computer. 
Hi, we purchased an inspiron 545 desk top in 2010 and have run it on broadband plugged in.  We now need to run it on wifi.  Does anyone know how to do this?  We have upgraded to Windows 10.  Thanks : - )
Inspiron desktop 545