How do you create a TFT composition on an online site?
You can make a composition on TFT thanks to the site : LOLCHESS.
You can add items as well as champions.
If you want there is also Overwolf which does it and adds you in game a HUD of items and everything: OVERWOLF.
What is LOLCHESS?
It's a "tft builder" site that lets you create your compositions in advance.
Return to the TFT WIKI and the list of patches: