Starting out
Here is where you should start off, however, you will need basic PHP knowledge to start off. If you don't have any or very little PHP knowledge I suggest you go through this tutorial and come back once you understand.
Now, you will also need to sign up for a 110MB hosting account, which is free if you have not already.
Okay, I think we are set and ready to go.
First we need to actually connect to the SQLite database, you don't actually have to make a .db file, it does it automatically.
$con = sqlite_open("database.db");
That will set the variable $con as a handle, which will allow us to manipulate the database later with the sqlite_query function.
Before we move on to actually querying into the database, I should show you a few more things about sqlite_open, that can help debug if need be.
$con = sqlite_open("database.db", $mode, $error_msg);
Obviously database.db is the path to the database file, $mode is the mode of the file 0666 is the default, this is like Linux File Permissions, 0666 wouldn't/shouldn't allow you to write to the file, however, it is currently ignored by the PHP Function, so you can just leave the variable $mode as is. As for debugging information, $error_msg is where the error message is stored, I recommend doing something like this to echo the error message if one is set:
if(!empty($error_msg))
echo $error_msg;
If you do not fully understand how this works after this, you can check out the PHP page for sqlite_open