I have Lightroom 4 and am wondering how to update it to latest version. Do I simply download the latest version? If so, will all my photos from the Lightroom 4 automatically transfer over?
If you are truly talking about the "latest version" of Lightroom, then you are referring to Lightroom Classic CC. It is a subscription-based Lightroom. You cannot simply download it, but you must subscribe to it. In the US, the cost is $9.99/month, and it includes Lightroom as well as the latest Photoshop. When you install Lightroom Classic CC, the first time you run it, it will find the catalog you have been using and will prompt you to upgrade the catalog. You should allow that to happen. The upgrade process will create a new copy of the catalog that is compatible with Lightroom Classic CC, leaving your original catalog intact and usable with the previous version of Lightroom that you have been using. I don't know if this is what you are interested in. But that is how you move to the latest version of Lightroom.