What you are asking will not fit as one comment here. I suggest you start here with this great page that has a ton of resources to help you get started: https://teach.udemy.com
Best of luck,
Please allow me to begin with "How to start with the course creation":
I use Camtasia 2018 on a PC running Windows 2010 with a Blue Yeti microphone to record primarily screencast software demonstrations and Microsoft PowerPoint 2016 presentations.
1) What operating system are you running on?
2) Have you selected screen recording and editing software?
3) What microphone will you be using?
These are the initial/essential questions regarding your course that need to be answered up front for anyone to provide useful guidance...
Welcome to our community and accecpt my warmest congratulations!
It's my honor to help you to create your best course.
I'm ready to help you to create great courses or increase the quality of your teaching.
The most important matters in teaching are:
1-Enjoy the teaching!
2-Consider you are teaching to children so say everything in depth and in simple language!
3-Try diffrent methods to delivery your concept.
4- Be expert in your field of teaching.
For recording :
1- You can use something like this:
but i'm using external sound card for connecting my microphone.
2-For better quality of your voice you can use Audacity Software and use it's noise reduction filter so the result is great.
3- For capturing your screen you can use : BB flashback pro.It;s really great app.
5- In addition you can send your test video to Udemy review team they are great and will help you a lot and also you can post your video here so we can help you.
6-Also you can use Udemy help center with great topics in this link:
7-Open My courses so there is few great Udemy free courses for how to create your course.
8- Don't worry anymore just focus on your recording and do your best.
Remeber this: practice make perfect.