Choosing within programming & computing
Choose by the kind of problem you have. If you are working in a particular language and need concepts explained or your code reviewed, start with programming help. If the difficulty is the logic itself (an algorithm you cannot follow, a complexity question or a bug you cannot locate), algorithm explanation and debugging is more focused.
Projects bring different needs. Software project and documentation support covers requirements, design reviews, UML and documentation from README files to full Sphinx or MkDocs sites. Database design covers modeling data as entities and relationships, normalizing tables and writing correct SQL, for courses and research datasets alike.