wow only 1 single baby? thats rough lol..
i've found that as long as you have plants these babies really take care of themselves! their instincts are quite impressive
if you do not have a planted tank you should really consider it! I have many livebearers in my 75 gal. planted tank, and i keep rooted plants in it and floating plants especially for the fry. They will grow up faster if they have the free roam of a large tank.....even though they dont freely roam!
A great quick-fix to not having a planted tank, but wanting a safe-haven for the little guy would be to just buy some hornwort floating plant at your
LFS. some stores will sell this plant as if its anchored in the ground growing, but it does not develop roots, and is indeed a floating plant. Buy a bunch or 2 of this stuff and drop it in your tank. I would wait for a bit as your fish will want to check out this new addition that they've just had in their tank. After maybe an hour they should get the idea of what it is.. I would then feed them a rather moderate amount of food as it'll keep them busy (i usually do flakes because some floats but a bit of it sinks also), and while they're busy eating plop your baby in the midst of the floating hornwort!
this may sound rather risky to anyone whose new to keeping babies but its pretty amazing how it seems the least paranoid we are, and the less we try to make sure our babies live, they better off they truly really are!
hope this helps!