how use SPSS for calculate dunn test??

if you referring to a Dunnett's test or dunn test? A dunn test is identical to a Bonferroni correction, whereas a Dunnett's test is similar to a Tukey, but is used when making particular comparisons to one group.

In SPSS when you conduct analyze-->compare means-->post hoc tab you will see Bonferroni and Dunnett's test. Or you can select analyz-->general linear model-->univariate-->post hoc tab and also see Bonferroni and Dunnett's test.