A transformation can mean a few things. A lot of times it deals with the spacing of the data points on one or both of the axes. If you want to shift a plot to the left a number of spaces, then put the x in parentheses and add that number of spaces. If you want to shift the plot to the right, then put the x in parentheses and subtract that same number. If you want to shift the plot up, then add that number to the entire right side of the equation (assuming the y variable is isolated on the left). You can also skew the plots. For example, make them steeper or less steep by multiplying the right hand side by a number or dividing the by a number, respectively.