Start up aeond and let it sync fully. Once it's safe to open simplewallet it will tell you that in aeond. It may take a number of hours to sync fully if it's your first time and you have less then blazing fast internet.  Once it reaches that point you can open simplewallet, but leave aeond open until after you close simplewallet. Always type "exit" in both programs to close them or it won't save things and you will have to resync.