Hello,
I'm a university student who was given a task by a lecturer to do several tasks by using no other software than OpenModelica.
The subject is called "Basics of automatics" and this task was given to me in exchange for passing the classes.

The problem is, we had no mention of OpenModelica during our lectures and all I have been told by the doctor is the name of the software I have to use.

And that's how I arrive at this point. I've downloaded OpenModelica and tried to grasp anything out of it, but, honestly speaking, to no avail. I still know nothing about it, even after checking out some guides or tutorials I've found. I hoped it would be at least a little similar to SciLab, which I am more familiar with, but it's not.

So, if anyone could tell me how to do what I'll write below, or at least guide me towards some place where I can find the answers, I'd be very grateful. This is all pretty basic stuff and I would have no problem with any of it if I weren't restricted to OpenModelica.
1. Plotting two graphs in a single frame, one of which is a simple graph of a function, while the other is a step response over time of a system of a given transmittance.
2. Plotting an impulse response graph of a given transmittance (I assume it's very similar to what I typed above).
3. Calculating a natural logarithm of a number.
4. Setting up a scheme of an open/closed system of a given transmittance.

I'll appreciate any help.