First time using ovulation test, please help?

Kayleigh • I am 21,Married with a 2 year old and a 1 year old boys and pregnant with #3 hoping to add pink to the family!
I'm getting hubs to bring home none digital ovulation test on the way home from work since I'm having trouble figuring out exactly when I am ovulating. Once you test and if it comes up positive, does that mean start having sex or does it mean you have ovulated and it's already too late? A test is positive once the second line is the same color as the other line? Sorry I've gotten mixed answers and I don't mean to sound dumb LOL I'm not the brightest at times. If someone could explain this to me it would be great. I've never had to track ovulation or anything it just happened with the first two kids, so this is all new to me! Thanks ladies in advance :)