Make Instruction for Windows application,App or Video?

I have a program called stopwatch and it is programmed with c#,Visual Studio asp .net. I want to have a instruction for this app so everyone can use the app easily without having to explain to each person in my company. I don't have access to the apps code. I can make video instruction or PDF instructions. But it would be great if there is a software to make an interactive instruction. For example: when the app starts, a pop-up would come up and tell the user to click on start button. Then waits for user to click on the button so it can go to the next instruction. Is there any app that can help me achieve this? Thanks in advance :)