Some basic concepts:
TCAD uses "model space" as the place to make your models of things, and "paperspace" (of which you can have several) to put views of the model on a sheet of paper. You can easily print the paperspaces and they will be What You See Is What You Get - like Microsoft Word.
You make a model in model space, and then you take "views" of it and put them as "viewports" into paperspace.
Model space is like a window into the real world. Models in it are the same size as the real object would be, but you can make the window closer or further from it as you like so you can see the whole thing or just a bit. Viewports are windows into modelspace.
So in model space, make a block by finding the 3D icon and drawing a block. You will see at the bottom of the screen little boxes that can contain dimensions to tell you how big the block is - you can directly write into them by clicking on them, or else you can drag the edges of the box with the mouse. It is much more accurate to simply write into the little boxes, that way you get the block exactly right. Make sure you have numbers in all three of the boxes!
Look at it in a perspective view, and you should see it as a "wireframe". You can "render" this view by selecting one of the possible renders, like hidden line which removes the lines on the other side. You can select "Make viewport" and drag the viewport box around so the block is within it, and then you can go to a paperspace and place the viewport on the paper.
Another new concept: "workplanes". Because the screen is flat, you can't tell how far into the drawing anything is. You can only drag the mouse around on the 2-dimensional surface of the screen, of course. So TCAD allows you to choose which plane your drawing elements should be on, and you can change this plane as you like. There are many ways of selecting a plane - such as "Select by facet" which puts it on one of the facets of your block, or "select by three points" which allows you to put it on one of the facets but with the XY coordinates the way you want. Once you've done that, you can put drawing elements on that new workplane. You'd want to do this for putting dimensions on each face of the block.
Another new concept - "Layers". Those dimensions are going to clutter up the picture of the block, and the ones on one face are going to interfere with the ones on a different face in your view port. You get round this by making new layers - which you can call something like "Front dimensions" or "Left side dimensions", and put the appropriate dimensions on those layers. Then in paperspace, you can go into the properties of your viewport and select only the layers you want to show.
You can put several viewports on one sheet of paper, so you can get a front view and a left view of the same thing on the one sheet.
Everything is configurable - the program is extremely flexible. Maybe you want three decimal places on your dimensions, and you want them to use bigger fonts or smaller arrows, or whatever - go into properties of the dimension (by right clicking on it and selecting "properties") and play.
Play with the program a bit, and then go through that list of tutorials. It will all get clearer, and whenever you run into something you can't figure out, ask a question on this board.
Hope this helps.