Adding onto a string is called concatenation. There's two concatenation operators in Torque: @ and " SPC ". @ will link two strings together directly, and " SPC " will link things together with a space in between.
For example:
%var = "blue" @ " " @ "elephant";
or:
%var = "blue" SPC "elephant";.
The reason I'm referring to the concatenation with space operator as " SPC " is because it requires a space before and after "SPC". So, while all other operators don't require a space (e.g. 5+2, "hi"@"you") that one does.