I'm not familiar with the approval process for children's ebooks at PubIt! but I imagine the reason for it is simply to protect kids.
Regarding your illustrations: What you will ultimately need is a digital image of each illustration. Jpeg (jpg) files are the most common and you should use the least compression possible in order to keep the quality high while keeping the file size under 5 MB. The resolution should be high enough to look good on a Nook HD+. The Nook HD+ has a 1920 x 1200 pixel resolution and a many artists size their full-screen images to 2000 pixels along their longest dimension (2000 pixels is the maximum PubIt! allows). Yet the detail cannot be too fine or it will be lost when the image is scaled down for a Nook with a smaller screen.
As for the ebook, itself, I believe its total file size must be under 20 Mb and PubIt! requires a portrait orientation. They usually want the aspect ratio to be in the vicinity of 4:3.
There are three approaches to creating the digital images:
Approach 1: Create the illustrations "old school" with traditional media. Then scan them with a digital image scanner to create the digital copies you'll need for the ebook. (An alternative to scanning, if the original media is either very large or three-dimensional, is to photograph it with a digital camera.)
Approach 2: Create the illustrations with a computer. The advantage here is that the images are digital from the beginning. But it can take greater skill on the part of the artist to create the images this way. It can also take more time. Most professional digital artists use a combination of Adobe Illustrator and Adobe Photoshop software for this purpose. These are expensive programs that are usually beyond the price range of amateurs. Fortunately, Adobe has a modest-price, consumer-oriented version of Photoshop called "Photoshop Elements" that might be helpful. There are some freeware programs like Gimp which have a pretty good following but be prepared for a steep learning curve.
Approach 3: Use a combination of (1) and (2). This is what I sometimes do. I'll sketch a drawing with pencil on paper. Then I'll scan it and use my digitized sketch as a template to redraw it in Adobe Illustrator. Believe it or not, this saves quite a bit of time if the illustration is complex. Then I apply the shading, color, texture and effects in Illustrator and Adobe Photoshop. I usually prefer to do text effects in Photoshop because I like its blending options better.
Finally, you will find more information in the FAQs and other help documents located on PubIt!'s support page. (Click on the "Add/Edit a Title" link under FAQs.)
Kind regards, David
Pubit doesn't have an approval process for kid books.
I used Word 2003. Page size 8 1/2 by 11 inches. 1 inch margins all around.
I did a page of text, did a page break, you can use section break and inserted the image into Word. It sizes to the page. Hit page break again.
I put the entire text into the document and used the breaks to insert the images.
Use JPEG as the image format.
I just uploaded two children's picture books. They worked fine with some help from good people in this community! I found that the main problem was to get the pixel count right. Some of mine were too high and when I lowered that count to below 2,000 they uploaded OK. They were all JPEGs
Have a look
I'd love to know what kind of puicture book you want to make!
Best to you,