Sometimes, a relative clause doesn't just describe a single noun—it reacts to or comments on an entire preceding sentence. In English, we typically use "which" for this (e.g., "He got stage fright, which was a problem").
When this "which" requires a preposition (like "about which" or "with which"), German uses a wo-compound. These clauses are called continuative relative clauses (weiterführende Relativsätze). Because they are relative clauses, they send the conjugated verb to the very end of the sentence.
Referring back with worüber
If the verb or adjective in your relative clause requires the preposition über (e.g., lachen über, sich ärgern über, sich amüsieren über), you will use the compound worüber.
Notice how worüber points back to the entire situation described in the first half of the sentence, rather than just pointing to a specific noun:
Referring back with womit
Similarly, if the phrase in your relative clause requires the preposition mit (e.g., ein Problem haben mit, zufrieden sein mit), you combine wo + mit to get womit.
More Practice
Remember that worüber and womit act as subordinating words here. Whether the clause has one verb or two, the conjugated verb must go to the very end of the sentence.