You might wonder if this is going to be one big baseball analogy, well, yes it is going to be. Clinical trials can be confusing and this is the best way I can think to explain it. I'm not a baseball person though so if I'm way off base (see what I did there) please let me know! I think baseball is best because most people understand the general concept of baseball if for no other reason than that it is used to refer to "how far you went" with someone back in the day. There might not be anyone who knows what the bases are but we all understand the concept of Home Base being the furthest and First Base being the closest right? Here goes nothing...
Up to Bat
You should hear back from your contact, if you don't contact them again. It is important to be your own advocate here. If the contact thinks you are a good match for the trial than you get a hit and advance to first base. If something happens and you are not a good fit then you strike out and start over again to step back up to bat.
I'm hoping to make it to second base right now; second base is the treatment period. During the treatment period you will receive whatever treatment protocol the clinical trial calls for. Simple as that. You will need to go into all your scheduled appointments, watch for side effects, and take all your prescribed medications but in this phase you are simply being treated.
If you have made it to home plate, congratulations! In this analogy the clinical trial worked and your cancer is shrinking; you will typically remain on the trial. Each clinical trial has a different time frame and exit procedure. If you come to the end of the trial you will have to follow the exit procedure and monitoring.