#curl this site and set to variable
price = curl https://www.usdsat.com/
#We need to extract data in a predictable way. I'm guess, but look at the output yourself, that the line "1 US dollar is currently worth" is going to be its own independant line. From here we can extract the number.

price = price.split("\n")

#line 16 will probably contain the line we want, but verify. If this method is not predictable, don't use it. I'm using ruby as my example language. ruby sets the first object to 0 so to get the 16th object we will extract object 15
price = price[15]

#price should now be "<center><h3>1 US dollar is currently worth <span id="current">4,790</span> sats</h3></center>"

#Again we need to split this output in a predictable way
price = price.split(">")
price = price[3]

#Right now our output should be "4,790</span" So we still need to get rid of what we don't want
price = price.split("<")
price = price[0]

#Now price should equal "4,790". Reference this variable in your site. I assume an ERB syntax here (embedded ruby code used in ruby on rails)
<footer>
<p>$1 = <%= price %> Satoshi</p>
</footer>