Help me to use ovlation kit

Hi ladies m gonna use ovlation kit for 1st time I hv PCOS n m tryng from last 3 years ñ hv been on letrozole n metformin my letrozole cycle is is complete n I was ovlating when I was letrozole bt cdnt gt pregnant 😢 nw it's been 6 mnths n I dnt knw m ovlating or nt bt evry mnth n going through such stress dts y decided to use ovlation kit bt dnt knw hw to use it I gt boots ovlation kit wd 7 tests so plz guide me wich dys r best for test???