You need to call the Text variable part of textBox2:
textBox2 is the actual textbox class, that contains more classes and variables, one of which is Text (the text in the textbox). You will also find other classes and variables to change the textbox's properties, such as color and size. If your using Visual Studio, a drop-down with a list of classes and variables should show up once you type the .
Secondly, when using conditional statements (if, else, switch, case, etc.) you need to use the conditional equals sign (==) to compare variables. If you only use one = sign, it will set (in your example) textBox2 equal to "thought" and return true if the set was successful (or false, if not).
Hope this helps!