"I have created new pages and would like people to be able to leave comments"
To enable comments, go to Dashboard, click EDIT POSTS, then EDIT PAGES and you will see the pages you have added to your blog:

Click EDIT for the page which you want to enable comments, then at the bottom left corner of the resulting "page editor", click POST OPTIONS and in the options under READERS COMMENTS:

tick (.) Allow to allow readers comments, then click PUBLISH.
Update: Blogger seems to have blocked comments for static pages. I have tested allowing comments for some page and found that what many commentators complained about - that it immediately revert to not allow is true. In fact on previous pages where I have allowed comments and the Dashboard showed that there comments, however, on loading the page, the comments are nowhere to be found.
Note: Blogger is aware of the problem and is working on it. See Blogger Help Forum
Note: Blogger is aware of the problem and is working on it. See Blogger Help Forum