Xia,
The paragraph about the author on the back cover with be placed under cover jacket material in the p pages (Rule 2.8). Follow the print placement location of the “About the Author” at the end of the book.
As for the social media symbols, if this is the only reference to these symbols I suggest naming the symbols inside TN symbols and add a TN before stating that social media symbols are identified prior to web addresses. Such as:
TNfacebookTN joshpeckofficial
TNtwitterTN @joshpeck
Continue the good work,
Connie