Changing state of a line

I am a new user of PI in the context of trying to execute scripts, so here is my question/problem.

I work in a powerplant and have a PI display of our high voltage grid.

Some portions of our grid have options as to the source of power. What I want to do is read a tag value, and if the value is greater than zero, I want to change a line from dashed to solid and bold.

Basically it would be like this.

If tag XYZ > 1 Then line = solid & bold

If tag XYZ =0 Then line = dashed

I can (barely) read code and write it, so some basic examples would be great.

Thanks