The Drupal project is open-source, so if you have questions about or problems with the software, your options for finding answers and fixes are somewhat different from what they would be for commercial software.
There are several options for free support provided by community volunteers. First, some Slack channels, DrupalChat channels, local groups, and language communities encourage support questions, through on-line chat, in-person meetings, or websites (find out more about these on Section 14.1, “Connecting with the Community”).
Second, some (but not all) contributed module, distribution, and theme projects encourage you to post support requests in issues. Generally, projects that have a very large number of users do not allow support requests in their issues (Drupal Core is in that category), while projects with a smaller number of users welcome the occasional support question. Be respectful of developer time and read the documentation for the project before posting a question in an issue. On the other hand, all projects encourage you to use issues to report problems and bugs; see Section 14.1, “Connecting with the Community” to learn more about that.
In addition to those resources, the following sites provide free forums where volunteers answer support questions about Drupal:
If you prefer to pay for support (presumably in exchange for more extensive service or better availability), you can find service providers in the "Drupal Marketplace" on Drupal.org.