Are you talking about these lines?
Those are called scan lines.
They are a pattern file that you can get
Here. I made mine but these will get you started.
Unzip then to load in Photoshop go to Edit/Preset Manager/
Under Preset type at the top select Pattern then click load, select scan line pattern file then click done.. That's it.
If you don't know how to apply the pattern let me know and I'll walk you through it..