Though it is common that USB printers will be detected by Windows and installed automatically, this isn't always the case. Should you find that your USB printer is connected, powered on yet still not showing up, your best chance for success would be to visit the manufacturers website.
Since most of our printers are HP, I will use one as an example.
1. Open Chrome to Google.com and type in the model number and the word driver.
2. Review the listing and look for the link to the manufacturers website. Click the link.
In this case it MUST be HP.com
make sure to avoid other sites offering drivers such as below. Note that the site is hpprinterdriver.net/... not hp.com/... like above
3. Navigate the list of drivers
4. You can either look for a full software package which will include the drivers along with the factory software which may include things like scanner software, OCR and status monitoring or search for a PCL driver package as shown below. Download the software or driver package.
5. Once downloaded, click the download indicator.
6. You may see a window such as this open up. Click Unzip.
7. When the unzip is completed the software installation should start. Follow the step by step instructions making sure to make the proper selections such as USB or network depending upon the type you are installing. When the process is complete you should be ready to print.