I am playing virtual villagers 2 and I was wondering if I can make my population more than 40!!?

Have you looked around carefully for a third building site? You should be able to have a maximum of three huts, which will allow you up to 90 population. Between the "love shack" (where they go to conceive) and the second hut, just about somewhere in-between there, you should see the outline of a building site that you can then build a hut on.