You have received a lot of great advice thus far.
Some things to keep in mind...
1. At first you will need to begin one subject or topic at a time and gradually introduce each into your schedule.
2. Don’t try to recreate school at home. It’s more stress for you than it’s worth, and chances are that the children will not respond well.
3. read, read, read. Read as much as you can stand to and with the children.
4. Go to the library and ask the librarian about homschooling reference materials. These days libraries have pretty good resources for homeschoolers.
There are many quality Bible studies out there. Bible studies can get expensive. Our first year we used the Calvary Chapel Bible study for kids because it was downloadable and it was free.
We also used a science curriculum called Considering God’s Creation. It was great - plus it was Biblically based.
There are so many math programs available that your eyes might pop out. I am going to recommend a math tutorial for you. Once you get your children up to speed, you can then choose what program best fits your children. I recommend ** http://mathmammoth.com ** because these are inexpensive, topic based e-books. There are many free worksheets your can get from that site to help you decide if it’s what you need. They are not grade specific, though the site does also have grade level options. Once you go through one or two (or however many you need) of the books, you can move on to grade specific programs like SaxonMath, RightStart, SingaporeMath, Math-U-See, Miquon Math, etc. Another resource for math is http://livingmath.net - literature books about math. You may want to read some of these books with your children over the summer.
Lastly, an easy way to know what to teach when - check out the CoreKnowledge books “What Your ——th Grader Needs to Know” This is a classical approach to education. I know that many charter schools in Colorado use these books to develop their own curricula instead of going with published curricula. I use it as an outline to know minimum standards of what to teach each year. It’s a good place to start.
Do not forget to check your state for legal obligations. Some states are more homeschool friendly than others - they may have requirements that you file with the state as a homeschooler, or that you send your grades in, or even that your children have to take standarized tests.
I forgot to mention phonics - It’s a time investment but worth it to use Spell to Write and Read.
Saxon Phonics is okay, but SWR teaches using the most commonly used words in the English language and teaches all the sounds each letter or multi-letter phonogram makes. The goal of the program is spelling and writing. The side effect is reading. A good reader is not necessarily a good speller, but a good speller is a good reader.