1 - 我在公园里边。
2 - Q: 蛋糕在哪里？A: 蛋糕在桌子下边。

Love the effort bro! First tip is to work on the pronunciation of "z" sound in zai (在). It's a hard one but doesn't have as much of a "t" sound as your giving it. Also, "park" is gong1 yuan2 (公园); whereas, it sounded a bit like your were saying gong4 yong1. 

Keep practicing my friend!