Here are two verbs conjugated in simple past tense. First comes the verb stem, then the past tense suffix and at the end comes the personal suffix.

First person singular is always -m

Second person singualr is always -n

Third person singular (he, she, it) doesn´t have a personal suffix.

First person plural is always -k

Second person plural can be -nız,niz,nuz,nüz.

Third person plural can be -ler,lar

ben git+ti+m
sen git+ti+n
o git+ti
biz git+ti+k
siz git+ti+niz
onlar git+ti+ler

ben koş+tu+m
sen koş+tu+n
o koş+tu
biz koş+tu+k
siz koş+tu+nuz
onlar koş+tu+lar

Build these sentences with a different subject.

Example:

These are given to you:

"Ali okula gitti."
"Ben ...  ..."

This is your answer:

"Ben okula gittim."