A simple straight line has the form of where m is the slope and C is a constant.
Can you work out C for yourself by substituting in your known values?
Slope-intercept form is where m is the slope and c is y-intercept.
So in your case we have
You can now plot some points from this function using a table of values, join the points to form the line.
or simply plot one point, the y-intercept and then use the gradient to find the direction of the line.
Do you follow?