Hi,
There is a If node in Dynamo. You plug in it your condition (which will be evaluated to true or false), and the two different values that can be outputed. Depending on the value of the condition, the If node will output the right part of the script.
There is also a CodeBlock way to do it : “condition? a : b;” means : “If condition is true, output a, otherwise, output b.”
There is also a ScopeIf node (which a do not recommend using, unless you know exactly what you are doing !) which will only evaluate the part of the script that will be outputed (more here : Node to stop / quit running dynamo graph)
The way you use those nodes/blocks will highly depend of the output you desire. If everything fails, you still have access to Python, which handle really way if statements.