Counting a Range

Hi guys, I appreciate this will be Excel 101 to most of you, but would appreciate some help. I have a range of data (example in image) which lists all the contracts we have and how long they have left to run. I would like to find a formula that counts how many days within a specific range of days remaining (e.g 0-30 days). I've tried working with the "COUNTIF" function but cannot get it to work. I used: =COUNTIF(B:B,"0,30"). Any suggestions, please ?Excel.jpg