Controlling a pattern is challenging:
First, when you clear them for takeoff, you will tell them to make right or left traffic. This is the direction they will be turning for the rest of the pattern unless you change it.
Second, after they depart you will give them a sequence. This tells them what number in line they are to perform a touch and go. For example, if the departing aircraft are second in line and the person who is first in line is on final, you would tell them “Number 2, traffic to follow is on final”.
Third Once they acknowledge this, you can clear them for the option. Clearing someone for the option allows them to do a touch & go, short approach, low approach, stop & go, etc. They will then perform from the list above and if they depart again, you repeat the process.
This image is a great learning tool to understand a basic traffic pattern.
Also, check out this link.
And lastly, check out this video!
Feel free to ask any questions!