I have Lightroom 5.7 and Lightroom 6. I have installed Lightroom 6 and it seems not to upgrade 5.7 but rather install a whole new version of 6.0. I am now wanting to backup my settings and catalogs and copy this to version 6 on my machine so that all my folders will be there as well as my settings
Launch LR6 and go to:
File >> Open Catalog
Navigate to your Lightroom folder (Normally in Pictures by default) and choose your previous catalog (.lrcat file)
You should get the option to convert it to LR6.