First of all a question that is asked by many students, children and parents starting to learn guitar.
What type of guitar do I learn on?
Well, basically for teaching beginners it is always a lot easier to use a Nylon string guitar, as it does not cripple the fingers too much like steel strings can, especially for very young hands.
If you already have experience with steel strings, and your fingers have no problem with this then that is fine also.
Now we come to how to hold the guitar.
The video here shows a variety of ways you can do this.
You can use some type of foot rest also.
Basically so long as the guitar is stable and does not slide around or wobble about, it will work.
Study the video and try a method that works for you.
Also as the picture here shows, there are guitar supports you can use too.
Naturally these methods are all for when you are sitting down.
This is how we start to learn.
Once you can play, and if you end up playing in a band, you would use a guitar strap and be standing.