There are two way, one is what SR said. Another way is to put it in a string itself. When PHP sees double quotes, it evaluates everything inside the quotes. So you can do:
$result = "$one$two";
Because it evaluates what's in the quotes, you can incorporate variable values into strings. So you can have:
$result = "I saw $one and $two the other day.";
That will print out:
I saw Roger Man and Johnny Boy the other day.
If you use single quotes, it doesn't evaluate it. So if you have the code:
$result = 'I saw $one and $two the other day.';
It will print out:
I saw $one and $two the other day.
So you have an easy way of incorporating variables into strings. The other way is to use SR's way, so it would look like:
$result = "I saw " . $one . " and " . $two . " the other day.";
Either of em works, it's just your personal preference. I mix and match, depends on how I'm using the variables. Sometimes it looks cleaner to use the . method, but sometimes I want to show that the variable value is a central part of the string. Your preference