I guess it depends on your own learning preferences, as to how you decide to learn these things. Some people open Inkscape and just start playing with it. That's a great way to learn some things. For myself, after that, I turned to tutorials.
First I would suggest Help menu > Tutorials > Basic, Shapes, and Advanced (and don't worry, the one named "advanced" isn't really advanced - really it's an introduction to what you need, if you want to make that drawing yourself).
After that, check out the Home tab above (in the forum, I mean). There are hundreds of tutorials linked there, and organized by skill levels. A lot of people use YouTube (sadly) (because there are way more bad video tutorials than good ones). But if you learn better visually, then YT might be better for you.
For drawing that....looks like a template for an airplane? You'll want to use the Pen/Bezier tool. You can change the width of the lines or the dash pattern using Object menu > Fill and Stroke > Stroke Style tab. Then of course the Text tool for the text.
Do you want to draw it completely yourself, or do you want to trace over that? If you want to trace over it, you can just import that image, and draw right on top of it. Although personally, I would lock the layer where the imported image is, and create a new layer to draw on. That way, you can hide the locked layer, in case you want to look at your work, without seeing the import.
If you want to draw it without tracing, you'll probably need some practice first. Just open Inkscape, enable the Pen/Bezier tool, click once on the canvas, and then.....whatever your heart desires! This is a tutorial I wrote a long time ago, about drawing a line (which apparently a lot of people can't figure out).
https://forum.inkscapecommunity.com/index.php?action=articles;sa=view;article=7To have all the sizes right, you'll need to make sure File menu > Document Properties > Page tab > Scale, is set properly. If you've never changed it, and you want to use mm, then don't touch it, you're good to go. If you want different units, change ONLY the Units. Don't touch the Scale.
If you have changed the Scale in the past, let us know. You'll need to do a little routine to fix it, and we can tell you how. But if you've never touched it, don't. Only change the units, if you need different units.
