GOOGLE SHEETS: Conditional formatting in Column M if corresponding row in Column B contains specific text

[giddyup43]

Hi. I am working in Google Sheets (is the formula the same in excel?)
I would like to highlight cell m500 if cell b500 contains the letters umb. I want this to happen automatically no matter if I'm in cell m600 or m7000.
Can you help me please?
Thanks

 

[etaf]

does this help
Use conditional formatting rules in Google Sheets - Computer - Docs editors Help

can you expand on what you mean by

I want this to happen automatically no matter if I'm in cell m600 or m7000.

as the site shows - you select the range you want to highlight

 

[giddyup43]

I want it to be the whole range of Column M, Based on the whole range of Column B. Not sure how to write the custom formula.