Purchase a digital chromatic tuner. You may be able to tune by ear eventually, but that skill takes a while for most musicians to develop. Take your time and work with one string at a time. Start with your A string and work from there to D, G, and E. If necessary, you can turn the tuning peg very slowly to adjust your violin further. If you need further help, Ronald Sachs Violins, staff would be happy to provide guidance.