get yourself a new coke bottle keep the top on and don't poke holes in the bottom. Move the light further away otherwise u will get a dangerous greenhouse effect instead of a humity dome effect. Don't worry about stretch and stem strength right now. All you want it to do is root. Even if it fell over that would be ok. It will pick itself up. Seedlings are tough. Most use clones.

You're gonna do great just don't overlove your plant. If you want more humidity spray the inside of the bottle with water.