It sounds like you've already looked at the company, it's strategies, goals and products, and how they want to interact with their users. That will help guide you.
You mentioned you haven't do logo design or web design before. Have you looked into visual communication? That's the practice of taking a message and conveying it in visual form. I did alot of this in college, and then dropped it to "get a real job". Twenty years later, I'm picking it back up again. I'd recommend getting books from the library, and looking up free courses online (there's one on coursera). Visual communication is the basics for turning the goals that you found into a visual message.
Another piece of advice I'd give is . . . just start. It won't be perfect. That's okay. Get okay with being imperfect. Just starting, at least for me, for lots of people, can be the hardest part. Then, like you said, you can iterate over and over again. Just start, and don't get hung up with your first idea. Make lots of ideas, then it's easier to break away when you realize it doesn't convey the message you intended.
And get lots of feedback! The feedback from your stakeholders will also help guide you.
I hope this helps you get started! All the best!