Query letter/Synopsis

Could anyone help me with the basic guidelines of writing a good query letter and/or a good synopsis.

I'm researching different publishing houses that accept my genre (mg/ya fantasy) and simultaneous submissions. Some of them ask for a query letter and some of them ask for a synopsis with two to three chapters.

I believe if I can just get my manuscript read, some publisher out there will have interest.

I hope this is the proper place to post this thread. I apologize in advance if it is not.

Thanks.

Hopeful, yes, but only young at heart.

Thank you for your suggestion. I will do that.