Which sentence correctly uses a colon?

I edited the article and found: comma splices, sentence fragments, and misplaced modifiers.

Anna was happy: to go skiing with her sister.

Talia decided that: she would accept admission into New York University over Harvard University.

I made just one request for the camping trip: I wanted to stay in a cabin instead of a tent.

This is what they told me: Because the apartment was too small, and cold for them.