My kids run their 99 zr 600 out of gas ,,my fault should have looked,but now it wont start what do I need to do...Thanks guys

I sometimes did this after my sled sat for a while.
(1) Put a few gallons of fresh gas in.
(2) (with the gas cap off) Put a rag over the filler neck and blow pressure into the tank.
(3) Pull it 4-5 times and it should fire up.

If the above does not work, take the plugs out and put some gas into the cyliners. If it fires up and stays running your in good shape. If it shuts off, see if you can now pull it a few times and get it running. If it wont, repeat the gas in the cyliners trick a few more times.
For every few seconds it runs its "re-priming" the system so to speak.

Find the coolant temp sensor. Unplug that, which makes the computer go full rich. The sled should fire up in 10 pulls or so.

I wil try all of this stuff tommorrow thanks guys,