Step #1 is ALWAYS to plan out your video a bit. You’ll want to gather some information and make some notes about the topic. If you have no information about the topic, it doesn’t matter how pretty your video is, because it won’t be good.
You can find some of your own sources of information, depending on your topic, but there are some that I highly recommend linked above. Please look through the information and MAKE NOTES. Take important events, concepts, people, devices, etc. and write them down in a Google or Word document. You need to have SOURCE LINKS for ALL of your information and content (photos, music, etc.) Those will go in the credits of your movie, but for now, they should be in your planning document.
Once you have enough quality information AND SOURCE LINKS, you can show me your document and then move on to making the video.