Keep in mind that the Unreal Editor is a very complex game development tool with an extensive list of features, not just a simple level editor. The number of features can feel quite overwhelming at first but a big portion of those are things you will never need to use to create maps for Urban Terror.
In general, the features you need are very well documented and there's a vast amount of learning resources for you to explore.
1. Intro to the Editor
https://www.youtube....e9Cx9wHoBB7rxFl
The Intro to the Editor playlist on Epic Games' (the company behind UE4) youtube channel might be the very first thing you want to check out. It's a few years old, but still explains the basics of the Editor.
2. Unreal Engine 4 Documentation
https://docs.unrealengine.com/
Lots of information is detailed in the official documentation. It's never a bad idea to read up on any particular feature or keyword you want to know more about. There's also a few quick start guides and small tutorials on there.
3. Epic Games Launcher Learn Tab
The Learn tab in the Epic Games Launcher has a few links to the quick start guides in the documentation I mentioned above. However, the real reason to check out the Learn tab is that it features a long list of example projects you can download and check out. All the assets in those projects are provided by Epic Games for you to use free of charge for any UE4 projects you are working on. That includes Urban Terror 5.
Of particular interest to anyone working on Urban Terror would be the following projects:
- Content Examples
This is something you definitely should check out. It's a project containing a bunch of demo levels showcasing a variety of features in the engine. You can directly see how things are put together and modify and play around with those features, instead of just reading about them in the documentation. - A few examples of really beautiful level design. This includes the Realistic Rendering, Sun Temple, Elemental Demo, Reflections and Particle Effects projects.
- Shooter Game
The Shooter Game project is a small but functional first-person shooter game with a nice looking map for you to check out. You can also use it as a base project for you to build your maps in, so you can easily jump into the game and run around for testing.
4. Youtube
https://www.youtube....pmentKit/videos
The official Unreal Engine youtube channel features a huge amount of video content of the engine developers explaining and showcasing pretty much every feature in the engine. Every major UE4 update also gets its own video where the new features are briefly introduced.
There's also a really big number of other people posting youtube videos explaining ue4 features and guiding you through tutorials of how to do certain things.
5. UE4 Answerhub
https://answers.unrealengine.com
The Answerhub is a place where ue4 users ask questions, report bugs and help each other out to solve those issues. Every beginner question you could have has most likely already been asked and answered here.
6. Google
https://www.google.com/
I feel this list would not be complete without mentioning that you can find the answer to almost any question you have regarding the engine by simply googling for it. You'll most likely end up on the Answerhub, the official documentation, youtube or the UE4 forums.
7. Unreal Slackers Discord channel
https://discordapp.com/invite/eNVW3Y2
The Unreal Slackers Discord channel is a chat room where thousands of UE4 developers meet, help each other out, exchange knowledge and showcase the progress of their projects. If you cannot find an answer to an issue you are having by googling, this is the next place to ask. There are lots of helpful people in there to answer your questions.
8. CMM Discord channel
https://discordapp.com/invite/t48GHkA
The Custom Map Makers discord channel is the community place where most Urban Terror level designers meet to help each other out and work on Urban Terror maps together as a team. This is a good place to ask about any urban terror specific mapping features.
9. Unreal Engine forums
https://forums.unrealengine.com/
The official UE4 forums contain lots of information about UE4 as well, but I think you'll end up here when googling rather than by manually looking through the posts.
10. Unreal Academy
https://academy.unrealengine.com/
This is yet another place that Epic Games has set up rather recently, which features video tutorials on a variety of subjects.