I used my tiller one time and the second time I used it, it was hard to start and when she did, she blew white smoke and would not start after that.

This happens frequently after a tiller, mower, snowblower, etc. sits for a season. Your tiller is probably flooded due to a stuck carb float. You can try a quick fix by tapping gently a few times on the float bowl, then pulling the spark plug and cleaning it with a wire brush, and then wiping it dry with a cloth. If you have a new spare plug to install, that is even better.
Try to start your tiller again, and if the same thing happens, your float is still stuck and you may need to have your carb serviced.
You can try one more alternative if you do not want to go through the bother and cost of having your carb serviced (or purchasing a kit and trying to do it yourself), but it is a 50/50 "hit or miss" sometimes it works, sometimes it don't type thing:
Drain all the gas out of your tiller. put about 2 ounces of carb/injector cleaner in the tank, and top off with gas. Give the float bowl a few taps. Now, pull the spark plug..... make sure the spark plug wire is at least 1 inch away from any metal. With the throttle set to full and the spark plug removed, Pull the starter cord 5 or 6 times (if you have electric start, crank it for about 5 seconds). You may see some vapors come out through the spark plug hole- this is OK.
Clean, install, and connect your spark plug (again, a new plug is even better). Give the bowl a few taps for luck, and try and start your tiller again. If the procedure worked, your tiller may run rough for 10 or 15 seconds (maybe even up to a minute or so... let it take its course!), but then smooth out.... if it stalls, don't worry.... Start it back up.
This will often work for tillers, snowblowers, mowers, generators.... pretty much any 4 stroke "lawnmower engine". It all depends on how badly the float is stuck after the engine sits.
You can minimize having this problem in the future (it may still happen, but less often and less severe) by adding a good fuel stabilizer (such as the brand name STA-BIL) to your gas and running for 10 minutes or so before you store your "lawnmower engine" for the season.
If you still have problems, the likely cause is a stuck carb float and the carb will need to be serviced.... but hopes are high that my solution helps!
Good Luck, and Thank You for using FixYa!