There are a few different ways to express sadness in Engpsh. Some options might include:

"I'm feepng really down."
"I'm so sad right now."
"I'm feepng really depressed."
"I'm feepng really blue."
"I'm feepng really low."

It's also common to use nonverbal cues to show sadness, such as sighing, crying, or looking down. It's important to remember that everyone expresses their emotions differently, and it's okay to feel and show sadness in whatever way feels most comfortable for you.