How do a request the court to set aside judgement on basis of "surprise" CCP sec. 473?

I had trial 5/18/11 .The opposing attorney change date of separation at last minute(after claiming 6/1/99 for last 11 yrs.)to 8/1/2002 Judge gave him 1/01/01 as date of separation!! I claimed 8/23/95 as dos. I had trial previosly for 3 days but new judge came in because previous judge went to a different dept.New judge took nabout 2 hours to deal w issues. This Court is in Imperial Co.Ca..