Ok just a few things:
First Next time please post some code here in the forum, don't use images! This 'cause it's easier to make a copy and paste of it and to explain you where's the problem.
Second in the image you posted there is an error and I didn't see it.
You are forgetting the "action" attribute.
echo "<form method='post'>
You should write like this:
You have to do this also if you want to post it at the same page.
echo "<form method='post' action='/path/to/your_page.php'>
The receiver page has to contain the code to analyze sent by post.
You'll pick up the value with $_POST['name_of_radio']
I post you an example of this concentrated in the same page:
You can see its working here
<form action="./test.php?key=1" method="post">
<input type="radio" name="test" value="1"/>The value of radio is 1<br>
<input type="radio" name="test" value="2"/>The value of radio is 2<br>
<input type="radio" name="test" value="3"/>The value of radio is 3<br>
<input type="submit" name="Select" value="Post your choice"/></form>
echo "Now I got the value of radio, it is $toprint";
I hope that's enough to help you.