Dear prabha,
Learning House Building is not too difficult. I advice you to involve yourself in construction sites if you want to learn the proper way. Then you can ask the workers, architects and engineers, which will be very valuable as they have hands-on experience on what you want to do. I do not know exactly which one of the many trades of the industry you want to learn, but if it's the drawing and building trades, then:
Learning AutoCAD first will be a fantastic choice. Ask your civil engineer friend for some architecture plans that you can re-draw on your own so that you begin to familiarize yourself with the software, it's preferable if the thing is already built so that you can compare the drawing with the built thing and realize how things are represented. Doing that will be amazingly valuable in your learning path.
Now, AutoCAD has a lot of features, but you don't see the workers using AutoCAD in the field, they use the printed-on-paper design/plan/blueprint, whatever. That's a drawing, a technical representation of the thing to build. If you can draw that, they can build it and so can you. There are, of course, rules for this. Each place in the world has a preference of how the drawing should look and what requirements it needs in order to be build-able. For instance, if you want to build a brick wall, you don't just draw a line. You draw a pair of lines that represent the element has a particular thickness in the real world, scales are too important to disregard. You also draw the towers, the places where windows go, the places where doors will be, etc. All those have a way of being represented on paper. A drawing is, in the end, just a bunch of lines, so the main commands that you will need are L for lines, PL for polylines, C for circles, CP for copy, M for move, O for offset, TR for trim, U for undo. You can do a lot with just these commands. Now, in a plan, you will also need to draw measurements, so DLI and DAL will be your friends. LA for layer arrangement and order and PLOT for when you actually print it. Try to hide as much of the interface as you can and familiarize with commands. Professionals usually don't need interface buttons to draw with AutoCAD.
And just like that, you can now begin your journey in construction. In fact, you can draw right now the space around you. Measure it well, draw a little sketch on paper with a pencil and annotate the measurement. Then go to AutoCAD and figure out the challenges, the things you didn't consider will begin to show up as you draw them, you will likely find out things aren't perfectly squared or heights are maybe irregular, those things happen, figure out solutions and keep on learning. Sometimes an elevation isn't even necessary if you write the heights of elements, but you know, it all depends. Also, you mentioned you want to fix some houses, I don't know how much you can accomplish by drawing the fixed version in AutoCAD, but it can help with planning. Perhaps you can also do some photo manipulation, even rendering. All of those will be very good skills to have. All architects must know them and it seems to me like you want to learn architecture. You can draw architectural plans and hand them to an engineer that can help you design more specialized stuff like Structure, Piping, Electrical stuff, etc. All of those can also be represented in 2D, you can draw them as well, but they require extra sensitive knowledge where lives are at stake, so let someone else handle the danger for you. I'm just being responsible here. Still, you can find some books in any of the three fields, look for design handbooks that use your local regulations and that will take you very far.
In fact, seeing that you're looking for books, don't take just any book as guidance. Look for LOCAL handbooks of architecture and other specialties. Things don't work the same in Asia than in America. And always fact-check ChatGPT and thumb it down when it misbehaves.
Someone mentioned REVIT here, I do not recommend using REVIT because it literally adds one dimension of complexity to your understanding, you do things in 3D. Sure, it can generate aerial views, elevations and rendering, as well as calculations but it's a cluster**** of features you don't need in your learning phase. Figure out AutoCAD first. 2D drawings are easy to understand and will help you enter the industry much faster. And most of the things you see were probably done when REVIT didn't even exist, so stick to the basics for now, it will take you very far.
You mentioned you want to enter the field because VBA is needed. There is indeed demand of developers, but also consider AutoLISP, which is the language most automation tools are written with, C# dot net and JavaScript as all of these probably have more demand than VBA. Still, go ahead and try. I consider myself fortunate to have skills in both software engineering and civil engineering, but my day job is as a civil engineer, so maybe I can help if you get some hiccups.
