Any help will be greatly apreciated
Somehow, I doubt it, but, here goes.
First, your code is posted improperly. You should be using the # icon (and see [ code ][ /code ] tags (without the spaces)), not the quote icon.
Second, the useless white space in your program makes it hard to read, as does stuff like this:
}}}}}
Each { and } should be on its own line. You need to use Tools + Auto format then to fix the oddball indenting, so the code is readable.
Third, meaningful variable names are important.
int stringthing = readString.indexOf("="); //here is a key component of where the status is being read by the arduino
That comment means nothing. stringthing? Something more useful, like equalPos, would make it clear that you know what the code is doing.
client.print ("<form name=input action= method= get ><input type= text name= form value= 'analog' /><input type= submit value= Submit /></form>");
There is too much wrong with this line to know where to begin. As with code, one statement per line makes reading a lot easier. There are quotes missing from this statement. That the compiler complains when they are added is no excuse for leaving them out. You need to escape them, instead (").
That statement starts and ends the form.
client.print ( analog );
This, then, just puts an unidentified number on the page, below the form. Why?
After you find the equal position (stringthing?), the rest of the string is the value of interest. String::substring() and String::toInt() bear looking at.