18 Year Old Caught Shoplifting From Wal-Mart

hey guys,
this is my first offence and to start off, i have learned my lesson..
but heres what happend
basically i was caught shoplifting for 38 dollars of merchandise and they wrote up my information, and i signed the banned from wal-mart and sams club paper, The police came and they got my infromation down and wrote down a ticket looking thing that said "if formal charges are pressed you will be informed of the arraignment within 15 days". So it's been 7 days and i still haven't recieved a letter.
What can i expect? How much will the fines be for a first offence misd.?
how many letters do they send you? and exactly how many fines do i have to pay other than court, and the main fine. Im only 18 and i'm trying not to let my parents find out. Im not gonna be able to hire an attorney and i'll probebly have to represent myself. Can any one help me?

There is no point in playing the "what if" game. When you get letter it will have a court date. You show up to court and request a Public Defender