Beginner Matlab Questions for Physics Lab Lowpass Filter Plot

Hello, I'm currently working on a task that requires the use of Matlab, which I am a complete newbie at - I've never even opened the program until today. Additionally, I have no computer science background at all. Literally none. I've never coded anything or been shown how to. I cannot emphasize enough that I have no idea what I am supposed to be doing here. A walkthrough of what commands to enter, what the commands should look like and and how to complete the given tasks would of course be ideal, but I would super appreciate any instruction at all on how to accomplish what is being asked in the problem below using the Matlab program. I really need to be able to learn how to use it to accomplish similar tasks in the future, but I've never seen any examples or walkthroughs before so don't have a jumping-off point.

I've included all parts of the problem below:

(a) For the particular lowpass filter you constructed in lab (f3dB ~ 11kHz) plot |H(f)| over the frequency range (0, 100 kHz) on a semilogarithmic scale for the frequency, and use a linear scale in dB for the vertical axis. To calculate |H(f)| simply solve for the output voltage in terms of the input voltage—it should be a simple voltage divider using the impedances of the capacitor and resistor. You will need to define an appropriate vector of frequencies.

(b) For a 200 Hz square wave with unit amplitude, plot the approximation to it found by summing the first four terms of the Fourier series (that is, to the 7th harmonic) over the first period of the square wave [0, 5ms].

(c) To see how a filter can distort a signal, repeat part (b) but plot the resultant signal after it has gone through the lowpass filter of part (a). To do this you will need to use |H(f)| to determine V out for each harmonic input (1,3,5,7), then sum those to get the result.

For part (a), I think I've made it most of the way, but I can’t figure out how to set the Y-axis to a linear scale, so if anyone knows how to do that some guidance would be greatly appreciated.

Parts b and c are the parts that I am stuck on and still trying to accomplish using Matlab, but I don't know where to begin. Thank you in advance for literally any help that can be given as I am quite stuck. I apologize for my complete lack of experience with Matlab and for basically needing someone to hold my hand through the process.