Need help with this certain circuit (RC phase shift system)

The design of the 741 opamp is 49 years old and it will not do anything with a supply as low as 5V. Also its inputs are not biased correctly and it has no negative feedback. It cannot drive a speaker.
Use an LM386 audio power amplifier instead. It can be powered from only 5V but then its output power is only 0.14W into an 8 ohm speaker. It already has its inputs biased correctly and has built-in negative feedback.

Your potentiometer is shorted. If it is not shorted then it destroys the phase shifts.

Look at "transistor phase shift oscillator circuit" in Google to see parts values.

 

Please describe "alternating sound".
The output of the oscillator and the amplifier is AC that is "Alternating Current".
If you want to increase and decrease the output level then use the potentiometer as a volume control between the output of the oscillator and the input of the amplifier.

Your potentiometer is shorted.
Your potentiometer has its slider disconnected from the circuit then adjusting it does nothing.

 

The pot in post #1 does not do anything because it is shorted out.
The pot in post #5 will vary the volume or loudness, but will not change the frequency of the tone.
An LM386 will *barely* operate on a 5 V supply. Read the datasheet to see the normal operating voltage range.

To your original question, this circuit is a sine wave oscillator. The component values depend on the frequency you want, and you have not told us that. If the intent is to add a potentiometer so the oscillation frequency can be varied, that is possible - but the adjustment range will be small.

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ALL electronic circuits need a supply bypass capacitor. Connect a 10uF to 100uF capacitor from +5V to ground.
Your volume control is backwards, it must be a voltage divider FROM the input TO the output.

The 3rd "R" has R1 and the input impedance of the transistor parallel to it which reduces its effective value. Therefore its value should be increased.

Your transistor oscillator has nothing to limit its output level so I think it will produce severe clipping distortion.

 

Why do you have a 10uF capacitor at the 0V circuit ground at the bottom of the circuit connected to another "ground"?
The output of the LM386 is missing the very important parts shown on the datasheet of the LM386 IC that prevent it from oscillating at a high frequency.
The capacitor in series with the speaker should be between the output of the LM386 and the speaker as shown on the datasheet of the LM386.
The +5V is missing a capacitor to ground.

Do you know how to properly bias the transistor?

 

I changed a few things.

Then the transistor probably will not work.

 

Why doesn't your "lecturer" teach you the basics of transistors?

 

Every transistor has a part number. Yours does not have a part number.
The datasheet for the transistor lists its specifications so that you can bias it properly. You don't have the datasheet.

Maybe you are not learning about electronics. Instead maybe you are learning about how to solder wires together?