I’d suggest learning what docker is and how to use it if you are trying to host it which is “installing” a web page.
If you want an icon to go to a dedicated window (web app experience) there are lots of options with lots of advantages and disadvantages. Just research progressive web apps. This method is going to require the frontend be hosted so you either need an instance that is using this frontend or you need to host it yourself.
Also to let you know. You’re getting downvotes because this is a very lazily asked question. You didn’t link to what it is you need help with, you asked the question in a manner that suggests you have done no research.
No hate since everyone is a beginner but I really suggest you spend a little more time crafting your questions to the community. Also read a little on docker and how lemmy front ends work.
I'd advise against using docker from docker.com's repo on Ubuntu unless you need to. Ubuntu LTS includes a fairly recent docker package starting with 22.04. By using that you eliminate the chance for breakage due to a defective or incompatible docker update. You also get the security support for it that comes with Ubuntu. The package is docker.io.