Yes compost bins need worms but these will be attracted by the decomposing vegetation provided a) they have access to the bin from the bottom and b) the compost it's self is not too wet. Remember it isn't the large garden worms you find in the bin but much smaller ones, these are brandlings and not so easy to spot.

Why are you sure that you don't have any worms where the bin is. The bin should be set upon bare soil. Is that the case with you or is it set upon something else, for example concrete or gravel? Aside from that turn your compost over every few weeks with a pitchfork for aeration and don't throw in any meat scraps; that will foul up the decomposition process and turn it into a nauseating mess.

Follyann: By now, the worms are most likely deep underground in hibernation. Do you have tackle shops in the UK - a fisherman's shop? If you do, you can pick up a batch or 'red wigglers' to add to your compost bin and see how quickly they multiply.

Seeing your question, took the lid off my bin but saw no movement at all. Then I dug my garden fork in and turned it over and there were hundreds of the little beggars.
You must have tried this ?