Once you volunteer at WikiTree you should start entering profiles of your parents and grandparents. Knowing dates/approximate dates and locations (Country - Province/Region/State) of b, m, d is most useful. You can ask living family members to help you with the basics.
Once you get a few generations - and learn the ins and outs of entering and editing profiles, sources etc. - you can expand on what you have.
One good source for general searches is Family Search - they have a free search tool at: https://familysearch.org/search, which can provide you with birth, marriage, death, census, military records etc. depending on the locations and timeframe.
Also, once you have a profile started, you can always ask for help here on G2G to get you further.