How to ask for salary increment ?

I am not a graduate, but I have been working at an educational institute for the past 10 months. Currently, I hold the position of senior faculty there, yet my salary is the lowest. Many graduates earn more than I do. Initially, I thought this was fair because I assumed they were more knowledgeable than me. However, that doesn’t seem to be the case. When we receive student feedback, my performance is often rated much higher than theirs.That’s not all—apart from teaching, I also handle a significant amount of additional responsibilities, such as marketing, system maintenance, and even higher-level administrative tasks. Given my contributions and performance, how can I approach my employer to negotiate a better salary?