Welcome to our community and accecpt my warmest congratulations!
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.