i wanna to know how can i recongize reject or accpet H0...

For example: 我計左個數 and compare with the t-table 果個數...is it accept H0 if my calcuable value is greater than the t-table value...

不過有時個數係負數,,,,咁我又唔知點啦...can someone explain to me about this

http://en.wikipedia.org/wiki/Statistical_hypothesis_testing

Basically in hypothesis testing,
the test statistics under the null hypothesis will follow a certain
distribution (in you case is the t-distribution)
And then you check whether the observed test statistics
lie in the critical region or not.
The critical region is the tail part of the distribution
which determined by the significance level of your test and
your alternative hypothesis is whether two-sided or one-sided