Don't know where to start with wooden dummy!

[WingChunIan]

In my honest opinion, whilst anyone can use a dummy to drill on you are limited as to what you can do until you've learned to step properly a la chum kiu. If you're desperate to use the dummy in some capacity and are still new to training, try taking all the bits out except one high arm and then practice your bong sau etc using the arm as a reference point. You'll know if your doing it wrong because you'll clash and the dummy will be the only winner. I echo what MJM said above, you shouldn't be bashing your arms into the dummy. Ip Man is quoted as saying once something to the effect of the person who makes the most noise on the dummy knows the least.
As soon as someone else arrives at class you are obviously better off going and pairing up and using real arms.