Welcome to the boards!
Pons gave you some great advice. I tend to request close to 50 PBs at a time from my library (it's great to ask a librarian in person--but a lot of the time I hear about great picture books here and other places online and add them to my library list). Try to concentrate on books that were published in the past few years, because those will reflect the current market. Current books (especially fiction PB) typically have sparse words (many of them are under 500 words).
There are tons of great writing books for picture books. My regional chapter of SCBWI recently ran an online class using Writing Picture Books by Ann Whitford Paul, and we all loved it (it's the kind of book you can read and learn from as a beginner then go back to it after you've worked on your craft and learn even more).
To start generating ideas, look around you and think about what could appeal to children. Or think back to when you were a child and what you loved, feared, dreamed would happen, etc. You can create a file for the ideas, put them in a journal, on scraps of paper (and hopefully keep them in a place you can find them easily when you want to use them). Try to write them down as soon as possible, because they tend to fade if you don't (I've lost some ideas that seemed awesome at the time because I was sure I'd remember them later.)
Here's a great challenge that starts in January that will help inspire you to come up with ideas. It used to be just for picture books, but this year it's changing to a new name (STORYSTORM) and will be for any genre. In the past, there were some amazing picture book posts that you might want to browse through:
https://taralazar.com/ Start writing, and don't forget to have fun! Collect as many ideas as you can, see which ones demand attention the most, then start working on your story! There are many ways to write a picture book, but one format that might help you start is a character who wants something, but can't have it...so the character tries three things and fails (each attempt even bigger than the last), and then finally finds a way to fix his/her problem. It's important for your character to do this on his/her own and not rely on adults or others to fix it for him/her. Then, see if you can end with something that's surprising or makes readers laugh--something that makes them want to read it again and again. By the end of the book, your character should've somehow grown or changed.