It helps if you have an example, like f(x) = 2x+3
What you typically do, is:
- draw xy axis, label them (ie., 1,2,3,4 along both axes)
- calculate the f(x) values for several x (e.g., -2, 0, 1, 3, doesn't matter).
- plot the calculated values as points. The calculated f(x) is your y value.
- sketch a smooth line through the points. It helps if you know in advance if the line is going to be straight or curved.
- The more points you calculate, the more accurate your graph will be