Wd-backup help?

can someone please help me?i have an older hp pavilion that is having hard drive issues,so i installed the new WD internal hard drive to see if it will help,is there a way for me to completley transfer my whole system over to the new WD?please help before my pc crashes completely 

If your old drive is still functional (you can see all data on it), you may use some software like Acronit True Image, Norton Ghost or similar to clone your old HD onto the new one. I recommend google-ing for a tutorial on “how to clone a hard disk”, since there are a lot of different programs able to do this.