OPK help

Hey ladies! This is the second month my husband and I have been TTC for baby #1. Also my second month off of birth control. I think I ovulated last month, but didn’t test so I’m not sure?? Yesterday was the start of my fertile window so I am going to start doing OPKs. However, I have ZERO clue how to use them. Do you have to test first thing in the morning? Do you test for several consecutive days? Is there an instruction booklet on how to use them? 🙈 if any of you pros have tips that would be great!! It’s all a very new journey for me. Thanks!