Here you can see how we can get the three main views of an object:
You can watch the video as many times as you need
And here you can find a link to a web page to practice how to obtain the views of an object
CLICK HERE
PERSPECTIVES
Watch this video to understand Isometric perspective
Apart from that, visit this website.
Isometric perspective an explanation
CLICK HERE
And
Isometric perspective summary
CLICK HERE
Some apps to draw using perspective