First off, does your computer say "Press [some key] to enter setup"? This would be the key you need to enter BIOS setup. Most, if not all computers will say this during boot.
If it doesn't tell you what key to press, I would first try F1. This is the most common key for entering setup. If this doesn't work, try all the other F-Keys, and if it still doesn't work, contact Dell again and ask for clarification of their email.
If all else fails, read the manual for your computer and see if it refers to which key is used to enter setup.
If it doesn't tell you what key to press, I would first try F1. This is the most common key for entering setup. If this doesn't work, try all the other F-Keys, and if it still doesn't work, contact Dell again and ask for clarification of their email.
If all else fails, read the manual for your computer and see if it refers to which key is used to enter setup.