CMS not working properly

[beeswax]

Last week I installed CMSMS in my webspace and had it working fine. In order to get the configuration in my head I deleted everything and tried starting again with a fresh database and a fresh install of CMSMS. I find I can't update pages/content unless I delete the page and start again, (though the updates I make appear in the preview) which is great if you get everything right first time, but if you spot a mistake... can anyoine shed any light on this?