SEO by Yoast problemen

Op mijn site https://www.mijnmemorandum.nl/mijn-laatste-wilsverklaring probeer ik de SEO optimaal te krijgen mbv de Yoast plugin.
Heb ook 2 images erin staan.
Heb na iedere aanpassing de cache gewist. Desondanks blijf ik maar zoeken hoe de SEO wel correct te krijgen.
Weet iemand hoe dit wel optimaal te krijgen.
Zou bijzonder hulpvol zijn.
Met dank al vast.

Hieronder de meldingen die ik niet kan oplossen;
Your focus keyword was found in:
Article Heading: No
Page title: No
Page URL: No
Content: No
Meta description: No

Page analysis toont volgende opmerkingen:
No meta description has been specified, search engines will display copy from the page instead.
The keyword / phrase wilsverklaring wilsbeschikking does not appear in the page title.
You have not used your keyword / keyphrase in any subheading (such as an H2) in your copy.
The keyword doesn’t appear in the first paragraph of the copy, make sure the topic is clear immediately.
The keyword density is 0%, which is a bit low, the keyword was found 0 times.
The images on this page do not have alt tags containing your keyword / phrase.
The copy scores 37.7 in the Flesch Reading Ease test, which is considered difficult to read. Try to make shorter sentences, using less difficult words to improve readability.
No outbound links appear in this page, consider adding some as appropriate.
The keyword / phrase does not appear in the URL for this page. If you decide to rename the URL be sure to check the old URL 301 redirects to the new one!