Could someone explain the use of oldum etc.

For eg.I became " oldum"

you became "oldun" i think

etc.

Thank you so much

The verb "olmak" has various meanings such as "to be", "to become", "to happen":

http://www.tureng.com/search/olmak

For example:

Hasta oldum -> I became sick

or

Bir kaza oldu -> An accident happened