You are not clear about your design,

So, I assume you are doing one way ANOVA:

Try this path:

Stat / ANOVA / One way ANOVA: put the codes of your treatments in 'factor" box and the response in "response"; click "comparison button", write the error rate: 5 for 95 and 1 for 99 percent confidence.

click ok twice and in results you have:

Treatment   N    Mean      StDev     95% CI

1                    3    5.000     1.000     (2.742, 7.258)

2                    3    7.33       2.08        ( 5.07, 9.59)

3                    3    7.667     1.528      (5.408, 9.925)

the data in 95% CI column are critical values.

Regards,