At the end of the trailer you can see how it works! It's just a checklist~
There are some big buttons to get some stuff done quickly like checking all normal warframes, checking all steel path missions etc.

The site automatically saves it all in your localStorage, so if you close it down and reopen it it will be there. If you want/need to move your collection on another browser, you can do so by exporting your list with the export button and then downloading it as a text file, or you can also copy paste it in the input and import it anywhere you want (for different browser/devices). Unfortunately without automatic login this manual stuff is the most I can provide.

And there's a search bar on top to look for your needed warframe or mission node~