I need help with itunes

Hello,

please help me. so i have over a thousand songs on itunes and i went to the apple website becauce i wanted the new version of itunes however i ended up downloading a new itunes. i got freaked out that all my songs would be earased so i turned off my computer in the middle of downloading. when it turned back on i tried clicking on itunes it said it had to be installed but if i install it is it going to earase everything i had on itunes before.? please help me.