It's very easy to rename the pages of your website. First login to your dashboard, and click on Manage Pages.
Then, next to the page you want to rename, click on the pencil icon:
Rename the page to what you desire, and click Save:
Now you can go to Preview Mode, and see that your page has been renamed.
If you want to change the page order in your menu, just click and drag the arrows in the Order column and drag the page to the position you require.
You can also change your page URL, view our guide on changing page URLs and Page redirects.