Help creating a logo

Hey guys, I am trying to create a logo for my youtube channel so I can use it as a watermark, put it in my background/thumbnail picture, etc. I really don't have any ideas as to what to do, but I just want to try and make a symbol/logo that represents me and has no copyright to it. (because it's a gaming channel I say that because I don't want pictures of game characters in it)
I really don't know what else to say besides I like the colors blue purple and green, don't want anything that can't be sized down and look good (as in I don't care if it's 100000000x1000000000 as long as it still looks good when put down to something smaller like 150x150 pixels)
Thanks for any help, if you guys need any more info just ask.