There is so much to learn, you simply can't make a good job of it by reading a couple of pages online unfortunately.
I would recommend that first you start off on a TEFL course to get some good basic ideas down. This will make your teaching more effective and give the students what they have paid for (if you're working already you can take an online one).
Until you get start that, here's some ideas.
1) If you are in a school the chances are that you'll have a coursebook. Is that right? If so, read it carefully before each lesson so you know what you'll be teaching and you will have a chance to prepare the grammar which comes up.
2) If you don't have a coursebook, do a
needs analysis to find out what you class needs to learn.
3) Seek advice off your DoS!