Welcome to the Blueboard, Esther!!
Your question is a bit tricky because children's writers who have websites usually have something to credit - - articles, a book, magazine contest win, etc. You might gain inspiration by going to the Good News thread and noticing which writers have gotten their first acceptances or publications. From there, you can visit their sites and see how they handle the About Me side of things.
All that said, you DO have something to credit!! You don't have to downplay your publishing experience, even though it's not yet in the children's world. In your bio, you could mention your book - and even link to it, if appropriate - and explain how you're now working on children's projects. The author websites I like the best include childhood photos and descriptions of their favorite children's books and authors from then and now. You could to that, too!!
Best, best wishes to you, Esther!! Have fun with it!!
(Disclaimer: I don't recommend my own blog as an example because I seldom post. The Blueboard is as about social as I get. Something I need to work on.....)