"加上标题" can be translated as "add a title" or "include a title" in English, depending on the context.
"Add a title" is more commonly used when you're instructing someone to create or include a title where none currently exists.
"Include a title" can also be used, especially when the context implies that a title should be part of something (like a document, presentation, or artwork), and you're emphasizing that it shouldn't be omitted.
In most cases, "add a title" is a straightforward and commonly understood expression.