The -lak, -lek suffixes express that the 1st PS does something to the 2nd PS or 2nd PP with a transitive verb. We’ve already talked about it in present tense: látlak, nézlek…
What about the past tense? Well, it goes like this:
Put the verb in 3rd PS definite past tense form and add -lak or -lek according to vowel harmony!
Látta. > Láttalak. – I saw you.
Nézte. > Néztelek. – I watched you.
Értette. > Értettelek. – I understood you.
Várta. > Vártalak. – I‘ve been waiting for you.
NOTE! The verb VÁR (to wait) can be transitive even if you talk about a person.
All right. We’re finished with past tense. Next time future tense.