Simple previous highest lowest price in period?

Hi, I am looking for a simple indicator that can draw a line as the moving average to say the higher or lower in some previous period price.

The entry will be how much time in the past?

For example:

At the moment the price is 5 front 6, 7, 9, 4, 2, 5, 8, 9, 7

Then, at the current price there is a line above the position 9 and the second line below him in position 2.

Please help me make this simple indicator ..

I can not believe I can not find simple things