Can someone please explain to me how to do vertical and horizontal shifts in sine and cosine graphs....

for example:

y= 1/2 cos 3(x+ pi/6)

y= -2 + 2cos 1/2x

I know how to find the amplitude, period, frequency and how much am i suppoused to do the shift by but i jst dont know how to graph it...
if someone can please help me i would really appreciate it....