YOU SAID:

I am walking to the market and I am going to buy an apple.

INTO JAPANESE

私は市場まで歩いていて、リンゴを買うつもりです。

BACK INTO ENGLISH

I'm going to walk to the market and buy an apple.

INTO JAPANESE

私は歩いて市場に行き、リンゴを買うつもりです。

BACK INTO ENGLISH

I'm going to walk to the market and buy an apple.