pls who can help with the procedure to flash a samsung duos phone?

Below is the general procedure for flashing Android phones, though I don't know if that of this particular phone is different.
1. off the phone
2. place your fingers on power botton, Volume down, and home botton all at the same time
3. press and hold all the three bottons until it powers on
4. select factory rest from the options.


REMEMBER TO BACKUP YOUR DATA BEFORE FLASHING

Thanks. Would try this. But how do I backup my data. Like apps and contacts.