Ovulation testing

I've been TTC since January 2015, my husband and I found out we were expecting in Nov 2016 sadly we lost our baby on Christmas eve. We didn't give up. We started right back at it. I've never done the tracking thing but after no luck and a lot of disappointment I decided to try the ovulation testing thing. Can I please get some advice from anyone who has used something like these? I started the tests 2 days ago and both didn't show anything, I think I saw a faint line on today's. Do I wait till the line is darker? Should we try everyday I see a line? When would be the best time to get busy?