Education:17 and i am going to the OB-GYN for this 1st time today and what exactly happens

First off, you cannot go if you are on your period. You may have to reschedule.
As far as the visit goes though...
first, they will ask about your family history and your medical history, if you are on any medications, ect...
they will want to know if you are sexually active and you mom will hear if she is with you.

next , they will leave the room and ask you to take off all your clothes and put on a hospital gown backwards, and lay down and cover yourself with a sheet.
they will give you some time and then come back to the room for the exam.

They will insert a speculum into your vagina, it may be cold and fill like a lot of pressure, it may be slightly uncomfortable, but try to relax as much as possible.
They will swab inside and send the swab to the lab to be tested.

next, the doctor will remove the speculum and insert 1-2 fingers inside you and place one hand on your lower abdomen to check the position of your uterus.

finally, the doctor will do a breast exam to check for abnormalities. this is just like a self breast exam

the whole exam should only take a minute, and if you tell them it is your first time going they will expalin everything to you as they go. If you have any more questions, you can call your doctors office and they can better explain what they will do.