Hello guys

I'm a newbie at crossbow hunting. I bought a carbon express crossbow and adjusted it at 20 yards no problem. I just don't know how to adjust it to 30 yards or more with the scope the store gave me with the crossbow. Here is a picture of my sight. What are the lines for? Usually on scope I should have the first point or line at 20 yards, 30 the next, then 40 and maybe 50 depending on the brand.

Thanks in advance

Phil