What wheredaluv described is more or less the way we do it. The formula is pretty much the same wherever you go. The variations are usually minor.
If you're a female, which I'm guessing you are, please do not wear a white shirt. You don't really think of things like that when you're being baptized but I can't tell you how many girls who we've had to stop so as not to embarrass them.
In our church, you don't have to be ordained, although the men who administer the baptism usually are. I am the leader of an outreach ministry that acts as a "church away from church" for sailors, fishermen, watermen and others along the Upper Chesapeake Bay. I'm not ordained but I would be the one to do the baptism there.
Here is roughly how it would go (although there is no set formula so it may vary)
1) After completing a new believer's class and a couple of informal counseling sessions, you would come to the marina where we hold our services in something you wouldn't mind getting wet.
2) We talk for a few minutes. I ask if there's any special hymn you would like to be sung. I then go into the baptistry (in our case, the boat ramp) and do my thing while you wait nervously.
3) I call you down and ask if you would like to give your testimony...you do...I say a few words...we sing the hymn you picked out...
4) I ask if you have accepted Christ as your saviour. You say yes. I tell you to cross your arms.Then, I grab your wrist and put one hand behind your back. I tell you that it's OK to hold your nose if you want to (for some reason, some people are really nervous and are afraid that holding your nose is somehow disrespectful to God...I have no idea why this is).
5) I say something to the effect of (and this may vary), "'Holly3278' I baptise you in the name of the Father, the Son and the Holy Spirit"...I dunk you
6) While you are under, I say "We have been crucified with Christ..." (don't be afraid, this only takes about two seconds), You come up and I say "...and raised to new life in Him".
The whole thing takes about thirty seconds.
We then end the service and go eat fried chicken.
My own baptism was pretty hectic. It was at Rancocas Valley Baptist Church in Willingboro, NJ and I don't remember why, but it was a last minute affair.
It was crazy but it was also one of the most wonderful and memorable events in my life. I hope yours is just as special.