Petty Theft in California

My question involves criminal law for the state of: california
I was caught two days ago stealing from a sephora in jc penny worth $197.00 and on the same day i stole from sephora in the mall worth $37.00, the jc penny found those items in my purse and i told them i took them from the store in the mall, they told me i am being charged with petty theft and that i will recieve papers in the mail and that i am to see a judge, i am a student and am so afraid of serving time in jail, i was wrong, i deserve to pay whatever fine and i deserve to be punished but what do i do to stay out of jail? do i nead to get a public defender? how do i do that? i am so ashamed of my actions, i have not slept or ate in these days i am just so deeply ashamed of what i have done. what do i do? i am 18 and have never been in trouble for anything. is it highly likeley that i will be put in jail? i am so afraid. what do i do?

also, this is the letter they gave me when the incedent happened it reads: this letter is to inform you that a report is being filed charging you with the crime of petty theft, 484 P.C.
the report will be submitted to the disctrict attorneys office for disposition. if it is determined that you will be held to answer on tis charge, you will be notified by an issuance of a warrant for your arrest.
upon reciept of this notice of warrant, immediatley set a court date by appearing in person at the following police facility, and goes on. what does this mean? will i be arrested? how likely is it that i'll go to jail? when i go to court, how will that work? if i plea guilty will i go to jail? or will they put me on probation or make me do community service? i am so embarrassed of myself, i have no dignity, no morals, i feel so disgusted with myself. i will never commit another crime in my life. i am just so afraid.