What can I do to update to the latest version?
Assuming that a user has a compatible CPU, updating, or rather upgrading, from Lubuntu 18.04 to 20.04 is not recommended. The reasons are set out in the release notes for Lubuntu 20.04:
Note, due to the extensive changes required for the shift in desktop environments, the Lubuntu team does not support upgrading from 18.04 or below to any greater release. Doing so will result in a broken system. If you are on 18.04 or below and would like to upgrade, please do a fresh install.
The extensive changes mentioned above relate to the switch in desktop environments from LXDE to LXQt. (Lubuntu 18.04 was the last LXDE version).
In comments to the question, the issue of the appropriate homepage for Lubuntu came up. The current official site is https://lubuntu.me/. For a bit of background, one could read this reddit thread in which the Lubuntu Release Manager responds to questions on a variety of issues.