Of course, one of the first and most important places to look for information about Unreal Engine is at the source. https://www.unrealengine.com should be one of the first places you look any time you need new information. You can get there via a browser or find the information in your Epic Games launcher.
Here are a few essential Unreal Engine links:
- Unreal Engine 4 Documentation: https://docs.unrealengine.com/en-us/—Start here always. Any time you're working with something new, give its relevant page a read.
- Unreal Engine Forums: https://forums.unrealengine.com/—There is a lot of useful information here, along with a huge population of forum users willing to help out others with questions. Jump in here and contribute constructively. You'll grow as a developer much faster with a community around you.
- UE4 AnswerHub: https://answers.unrealengine.com/index.html—When you're facing a specific question, search for its answer here. If you can't find it, ask. The key word here is specific. If you ask, How do I Unreal? that question clearly demonstrates you haven't done your homework, so you'll be ignored. Good questions, though, get good answers. Be willing to return the favor, too. If you see a question you know the answer to, jump in and help out.
- Unreal Academy: https://academy.unrealengine.com/—This is a series of focused tutorials geared toward specific topics of interest, either within the engine or out in the professional world. They generally take the form of a series of video lessons, and the quality is consistently high. This is one of the best places to broaden and sharpen your skills.
- Unreal Engine YouTube Channel: https://www.youtube.com/channel/UCBobmJyzsJ6Ll7UbfhI4iwQ—This is another resource many new developers overlook, but you shouldn't; it's important. Here's the thing: Unreal Engine is absolutely huge, and with hundreds of engineers working on it, along with thousands more in the community, it evolves and grows fast. Because of this, there's a ton of amazingly useful stuff in the Engine that just hasn't been documented anywhere because it's too new or too niche. The secret to finding this stuff are the Live Training videos on the Unreal Engine channel. These are nearly always given by whatever engineer wrote the system they're talking about or by a trainer who knows it really well, and they're a fountain of useful information. If you really want to learn how to use this engine, this is the place to do it.
- User Groups: https://www.unrealengine.com/en-US/user-groups—Get involved in the community of real-life people in your area. Find meet-ups and events, and then go to them. This is one of the biggest secrets we see new developers overlook—they don't put themselves out in the world. Whether you're looking for collaborators, looking to get hired, or looking to hire someone, you're doing yourself a big service by getting out there and participating in the community.
For more general programming questions, one of the best resources out there is Stack Overflow (https://stackoverflow.com/). It's not Unreal-centric, but if you're looking for information on C++ development, this is where you'll find some of the most experienced developers on the web. Be warned though—the Stack community is notoriously intolerant of low-effort questions. Be respectful of everyone's time and come in with a question after you've gone as far as you can to find the answer to it on your own. Describe what you were trying to do, what you did, and what challenges you faced. Do this, and you'll get some of the most reliable expert advice you can get on the web.