SPSS Weighting help please!

I'm struggling with analysing my survey results in SPSS and really hoping you can help.
I surveyed occupational therapists around aspects of their practice, on a national level and the seniority of the sample were made up of the following:

Band 5's- 8
Band 6's- 25
Band 7's-35
Band 8's- 6

This distribution compares nationally within the NHS to:
Band 5- 24% (3,214)
Band 6- 45% (6130)
Band 7- 25% (3336)
Band 8 -6% (838)

So, how do I translate this into SPSS to ensure that my responses are weighted according to seniority, ensuring that my findings have generalizability? I am currently analysing my categorical dat via chi square tests.

Thanks so much for any help you can offer-I've trawled through the net and nothing seems to offer straight forward advice!

Amy