Problems with position and size of ads by Google Adsense

Hi Support,

please check my website:
https://www.motivationsheld.de

Finally, Google has activated my Adsense account … As you can see, there are now ads on my website … So far, so good

BUT: As you can also see, those ads are looking terrible and are destroying the complete design and user experience of entire website.

TWO GOOD EXAMPLES ON THIS SCREENSHOT:
https://www.screencast.com/t/fsv3jmrT

1. The above ad is destroying the design of my footer! I don´t want any ad here
2. The ad below takes up a lot of screen space… I don´t want it

WHAT I WANT:
1. I want to determine WHERE exactly an ad is placed and where not.
2. I want to determine HOW BIG an ad will be sized in the desired location.

QUESTION:
How can I do that?

Thank you,
Oliver