Yes everyone has the ability to search, but most cant find the info so www.searchlores.org
this site will teach you the proper techniques on searching
basically ip spoofing works by constructing your own packet and chaning the source address and of course thats very simple in c\c++
You break down a packet into different sections and change them to suit what you are doing
Why do people use this.. Well there are to many reasons some use it on smurf servers... these servers reply 1000+ times for each packet u send to it.. so if you spoof the packet with a targets address it will send them 1000 packets for every 1 u send.. and some of these servers have some nice bandwidth so after like 100 packets u send there connection is dead and voila a good ddos..
but of course you shouldn't do this
its naughty lol