Help 1st time using OPKs!?

Hi everyone! I'm fairly new to Glow but have been TTC for 4 months, bbt charting for 2 months and decided this month to give an opk test a shot since why not. Today was my first experience with it. The directions state if the test and control line are the same color or control line is darker it's positive. If not it's negative.. well this morning I thought I maybe had a positive, but couldn't be certain so I retested this evening (I read some people test as often as 10 hrs apart, is this true?) But now I'm even more confused! If you have any input for me I would greatly appreciate it!!