How do I post some introductory paragraphs on the main page of my blogdown site?

I wish this help you I leave my answer here because it is directly what the OP asked for. The proper way to do this is to use python-wikitools as suggested in the answer by @ChristophD below.

import urllib2
import re, sys
from HTMLParser import HTMLParser

# EDIT 1: import the packag
from BeautifulSoup import BeautifulSoup

class MLStripper(HTMLParser):
    def __init__(self):
        self.reset()
        self.fed = []
    def handle_data(self, d):
        self.fed.append(d)
    def get_data(self):
        return ''.join(self.fed)

def stripHTMLTags(html):
    html = re.sub(r'<{1}br{1}>', '\n', html)
    s = MLStripper()
    s.feed(html)
    text = s.get_data()
    if "External links" in text:
        text, sep, tail = text.partition('External links')
    if "External Links" in text:
        text, sep, tail = text.partition('External Links')
    text = text = text.replace("See also","\n\n See Also - \n")
    text = text.replace("*","- ")
    text = text.replace(".", ". ")
    text = text.replace("  "," ")
    text = text.replace("""   /
 / ""","")
    return text

opener = urllib2.build_opener()
opener.addheaders = [('User-agent', 'Mozilla/5.0')]
infile = opener.open('http://en.wikipedia.org/w/index.php?title=Albert_Einstein&printable=yes')
page = infile.read()

# EDIT 2: convert the page and extract text from the first <p> tag
soup = BeautifulSoup(page)
para = soup.findAll("p", limit=1)[0].text

print stripHTMLTags(para)

This might help you I want to show a div with some buttons ,first time my site loads and I want that the site become not usable until that div closes with one of its buttons (like when you choose an image in image.google.com and after that you see the selected picture with the site it extracted from behind it but that site is a little dark and just like a photo of the site)

<div id="overlay">
  <div id="dialog">
    Close me to see anything else
  </div>
</div>

#overlay{
position:fixed;
z-index:9999;
top:0;
left:0;
width:100%;
height:100%;
background-color:rgba(0,0,0,.3);
}
#dialog{
width:200px;
height:100px;
margin-left:-100px;
margin-top:-50px;
left:50%;
top:50%;
position:absolute;
background-color:#ffffff;
border:1px solid #666;
padding:20px;
}

help you fix your problem I'm doing this for my classes. You can see the end result here, click on "teaching". You can see the source files in the GitHub repository. In particular look under the content/classes folder.

This might help you In hugo, the layout of the website mirrors the layout of the files in the content directory. So, if you have a blog post in content/blog/my-cool-post.md, it will show up as https://example.com/blog/my-cool-post.html
See hugo docs for a bit more.

I think the issue was by ths following , The width is determined by your theme. I only looked at an example site provided here but in this particular case, the element you need to deal with appears to be main-content-wrap. I came to this conclusion by right clicking on my browser and picking "Inspect Element" (firefox) or "Inspect" (chrome) which gives you information about which elements are present and how are they effected by existing CSS. From here you can see that it has a default max-width of 750px. You need to create a CSS file to overwrite this property. The file only has to contain

.main-content-wrap{
    max-width: [insertYourDesiredWidthHere]px
}

[[params.customCSS]]
 href = "pathToFileUnderStatic"