Many people use [
SketchUp] for their design work.
AutoCAD is powerful but as you have found out it does have a steep learning curve for a start.
The easiest way to draw things to scale is to use the offset and trim/extend tools.
Ok. Imagine for a start you are drawing your CP viewed from above. The first thing you would want to do is draw a rectangle of the basic size of the CP. Lets pretend its 500mm x 250mm
Draw a vertical line of any length for a start using the line tool.

Make sure you have Ortho turned on by clickling the little

button at the bottom of the page. Activating this means you can only draw vertical and horizontal line. Click on two places on the screen, one above the other, on the screen and you should have a straight vertical line.
Now use the offset tool

to offset the vertical line you have drawn. Click it and it will ask you what the offset dimension is. Type 500 and press enter. It will then ask you to choose and object to offset so click on the vertical line. It will then ask you to pick a side to offset the line so just click either to the left or the right of the line.
The line will then be copied and placed 500mm to the left or right of the original line. You may need to use the scroll wheel of your mouse to zoom in/out to see it.
You can use the line tool again to join up the bottom of the vertical lines. You will need object snap

switched on to do this. You may also need to right click object snap to choose which snap points to use. In this case you will need the end points highlighted. If you have done this correctly when you use the line tool you should see a little anchor mark appear near the ends of the line as your cursor approaches it. This means the line will snap to the ends of the line when you click the mouse.
You now have a horizontal line of exactly 500mm with two vertical lines at the ends. Use the offset tool again but this time enter 250 as the offset dimension. Now select the 500mm horizontal line as the object to offset and click above the line to offset it above the line.
More than likely the vertical lines will not reach the top horizontal line that you just offset. You can use the extend tool

to extend the lines to meet the ends of the other line. Click the button and it will ask you to select an object(s) to extend to so click the upper horizontal line and press enter. It will now ask you to select the objects to extend so click the ends of the vertical lines and they should extend to the horizontal line to make a rectangle that is
exactly 500mm x 250mm.
Alternatively if, when you offset the horizontal line, the vertical lines extended past the new horizontal line you will need to use the trim tool.

This is used in the same way as the extend tool. You select which line to use as a cutting edge, press enter and then click the parts that pass the cutting edge to remove them.
I know this sounds a little long winded but once you have done it a couple of times you will be able to do it in seconds. You could use the rectangle tool to do this but it would be a polyline and you wouldn't be able to offset parts of it etc
This type of thing is the basis of all drawing all of the basic parts of the drawing and for creating anchor points for drawing circles, chamfers etc etc.
Most of the tools will walk you through them and ask you for information.
If you want anymore help just ask. I am in no way a master of CAD but I use it a little to draw components etc and its what I have always used for my cab design. There may be better ways to draw things but these are the methods I use. I can get some screen shots of the various parts of this mini guide if you would like. I would have done it already but I am at work and I don't have AutoCAD here, I just copied the buttons from google images.