Hi Ann,
I'm making the assumption that you are referring to the most recent Creator Update, released on June 27, 2017, which will take you to OS Build 15063.447
These Cumulative Updates are released on a Tier system, based on Telemetry data Microsoft has collected from your computer from previous builds. They send the updates to the computers most likely to have no issues at all with the update first, then in time start releasing it to everyone else next.
You can click the Check for updates button, and see whether it is ready yet, but otherwise just wait a little longer.
Otherwise, if you are happy to install it, you can click the Learn more link on the Settings > Update & security window to be taken to a page where you'll be able to read what the update will do, and get a link to directly download it. If you do this, it would be wise to first backup important data/files just in case the update causes issues for you.