The idea is to use the heaviest weights you can for the prescribe sets/reps each day. You won't always be able to do more than you did the previous week, but you should be able to make increases for at least 3 wks at a time.
If you do you snatches at 50kg no problem on wk 1, yes, go up on week 2. do you first set at 50. If that's good, go 52 or 53. If that's tough, you can stay there for the rest of your sets. If you feel good, go 55 or 56 for the rest of the sets, etc.