After creating the minimal configuration file, you're more or less ready to run Squid for the first time. To do that, just follow the instructions in the next chapter.
When you've mastered starting and stopping Squid, you can spend some time beefing up the configuration file. You may want to add more sophisticated access controls, which you'll find documented in Chapter 6. Since I didn't say anything about the disk cache yet, you should also spend a fair amount of time in Chapter 7 and Chapter 8.