POD books don't make it into brick & mortar bookstores. Reasons - they aren't returnable, they usually cost more than other books, and often the covers are shitty, and yes, the cover does count. There's more, but I'll stop there.
Now, depending on what type of book you've got, it may not matter that you can't get your book into Barnes & Noble. If you've got a well defined potential audience, you may be able to reach prospective readers in other ways.
So again, do your homework. There's a ton of info out there. Read the two books I suggested in the other thread. They'll probably answer 99.9% of the questions you have, and point you to resources that'll answer the other 0.1%.