Are you a starting dev? well use scratch!

Scratch is no downloads  it cost NOTHING

I highly recommend for starters tutorials can help!

Scratch:https://scratch.mit.edu/projects/411027490/editor

I clicked the URL and it took me to nowhere.  Here is one that actually works: https://scratch.mit.edu

Also if you don't have any way to plan anything, you can use https://trello.com for easy stuff

(Not Sponsored, its just these sites are good)