Wiccan celebrate yule, its on the 22nd this year. its is the end of the dark half of the year and the welcoming of the light. The Oak king defeats his brother the Holly king and rule the land until summer. Almost all books will have information of this and the other festivals.
As for your BoS I would wait until you know a little more about Wicca first before thinking about this, personally I don’t have one, instead I have several note books and random bits of paper with things relevant to my path. There is no right or wrong way to do a BoS as it is a very personal item what you put in it i entirely up to you, Some people put ritual outlines in but you can find these in most books and as you practise you ritual will change and adapt to suit you, so I see little point in writing on down. I prefer to keep a collections of recipes, poems, invocations, stories, folklore etc which I can refer back to during the appropriate season, or use as inspiration.