Let me help you.
Last Sat(abbreviation of Saturday surely),I got up pretty early in the morning,brushed my teeth and washed my face.
I cooked & had breakfast on my own and went to the library.
I often go to the library at 8:30AM ,but last Sat I went to the library at 8:00AM.
The library was so much crowded.
I stayed at the library all day.
I returned home at 5:00PM.
So,what did you do last Saturday ?(About this sentence,you could also say this way
How was your last Saturday?)
In case you want to strengthen the meaning of an adverb,please do not use so much.
Instead of it,they use pretty,suprisingly,etc in America.
Just a little showoff of Native American English.
Hope you good luck with your future learning.
From kind Jay K.