joseph_e2 is correct.
But you Crimson won't let you type "Ready " and then drag a Tag in to the box, it just overwrites what you typed with the Tag. Not too terrible, because you drag the Tag in and then edit to get ="Ready " + Tag.
Instead of dragging a Tag in there is another way that keeps anything you type first. Go to your Tag list, right click the Tag you want in the Text Box, and copy, then go to the Test Box where you want the value and right click and past.