Don't worry too Much, it's really not a big deal. As it get bigger you can then stake it or help strength it (pinching, a fan, silica, etc).
For Now:
Get a very light fan breeze just above the top of the plant, and pushing from the side it's leaning over most. (As long as your temperature remains acceptable. This will help strengthen the stem.)
When you buy an Electronic Product, they usually wrap the wire/plug in a plastic/wire-tie. Use that tie to help create a "stake".
Make sure, if you use any kind of stake, be gentle when pushing down near the base of the seedling. You do not want to damage the root.