If you've been tasked with writing a web design brief for a new website, here's a web design brief template that might help you.
It's based on experience and research, and is geared to the SME or SMB market website. You might find that it doesn't cover everything that you need to include in your own brief but it should be a good starting point.
It's also worth remembering that the brief does require a good deal of thought - you should think carefully about what you want your website to achieve before you start writing your web design brief. You should also be honest about acknowledging the strengths and weaknesses of your existing website.