Basic joke construction goes as this, there's two parts:
1) the set-up
2) the punch
The set-up is when you start telling a story, and building the audience up..
The punch is where you suprise the audience, and add something that the audience would not expect...
For examples, look at just at about every joke you've ever heard...
Comedy is all about observing your surroundings and making interesting observations... It's not an easy thing...
Stand up comics will spend hours upon hours rewording jokes so they sound just right... It's almost like writing an essay. First you brainstorm an idea, then you write down every observation you can think of... then reword, and narrow it down...
A basic stand up rule is to make the joke seem like you just made it up...
But I assume you just want to learn to be C&F, well its all about observing, and commenting on your surroundings or something that is said...
You can't just learn a set of phrases and use them. Sach situation is different. But if you happen to make a C&F remark when a girl says something to you, don't be afraid to remember it, because odds are another girl will use the same remark some other time, and you can re-use the remark...
As for examples... there are thousands of funny movies, stand-up videos to watch. But I'll give you one of the first excersices form the comedy writing secrets book..
"Take two bottles of pop and put them together. Write down everything you can think of them".... It's all about thinking about the "logically illogical"....