switching routines

I have been excersicing for months now, mainly treadmill then some floor excersice anyway I just recently got a home gym with weights!  It's has 30 different work outs on it, I had a friend tell me that I probably need to switch out my routine.  So should I do arms and chest 1 day then the next legs and Abbs?  Or should i rest everyother day and then switch it out from arms to legs, I know it's important to rest so your muscles will grow i just don't know how much rest.