Custom size of objects and placement

Greetings everybody, so I am a total CAD n00b and never used software like this so please arm yourself with patience. :) Exploring wiki pages, YouTube manuals and .pdf manuals here did not do any good. I spend couple of hours already and no success to figure out this particular problem...
So first I am using LibreCAD 2.1.1 on Win7. Many manuals I found is for older versions so this is also some roots to confusion.

So my problem is I cannot set the size of the created rectangular object. I want some option or something to enter width and height and not to drag my mouse around as it is always missing for 1.2585 mm :P. Same is for the circle objects, i need specific diameter and option to place center of this circle on exact position in mm of the other object.

Hope you understand what I mean. Help please!

Look for the command line. Out of the box it is on the bottom of the right side. When you triggered a drawing command, let's say line of two points, you are asked in the command line to specify the points. You can set these in absolute coordinates (x,y), or relative to the last point, which then is 'relative zero' and represented with that red circle. You have to set an @ in front of the coordinates (@x,y). This 'relative zero' position can also be set to your liking by the 'set relative zero position' command. You might have to set the proper snapping mode for this.
For some drawing operations an additional bar appears where you can enter values. By default it is somewhere at the top. Watch out for this.

Thank you for your answer, this was helpfull! :)