Need AFL help

Hi Seniors,

I want to plot lines in such a way that the lines show up on:

1. 5% of High-Low added to yesterdays high.
eg: High=500 Low=450
High-Low=50
5% of 50=2.5
Line should plot at 500+2.5= 502.5

Same way second line 2.5 below 450
450-2.5= 447.5

I tried much but am not good in creating afls with such calculations.

Any help would be much appreciated.

Thanks.