Jerboa doesn't currently have a feature to search posts/comments in a community. The most they offer is search the list of communities. I'm sure other people want this as well, and the web-ui has it, so it's definitely possible to implement. I think just no one has gotten to it yet.
The last few jerboa releases have had a list of new contributors a mile long though, maybe somebody will grab this feature soon.
How do you use the web-ui I don't see any executable, launch file whatever. is this only for Linux? the jeroba apps is good. I know its in alpha but looking for all kinds of ways to interact with lemmy
If I'm reading right, your account is on https://lemmy.world/. So you go to that website in your browser and log in with your username and password. The web-ui is literally just the website of the instance where you created your Lemmy account.
Bottom bar, second icon from the left. Until very recently it looked like a checklist icon, I think as of today's update it might be a magnifying glass.
That brings up a list of your subscribed communities, with a searchbox at the top that searches all the communities your instance knows about (not just your subs).