I'm TTC and I need help figuring out when I'll ovulate. My period is irregular. The t line is…

I'm TTC and I need help figuring out when I'll ovulate. My period is irregular. The t line is lighter so that means there's no LH surge so what does that men and when should I test again? There's a pic in the comments of the instructions and it's just a dollar store test. I may sound silly but I don't quite understand how to do all this haha