What is a compound sentence is made up of?

Well a compound sentences is 2 simple sentences put together as one sentence by putting a connective inbetween.

Examples: 2 simple sentences: I went to the shop. I bought an Apple

a connective: and/but/however/although

Sentence together: I went to the shop and I bought an Apple.

So in a compound sentence you need atleast 2 simple sentences and a connective.