Independent samples t-test (Open University)
This free tutorial from the Open University shows how to produce an independent samples t-test. You will need to register to access the content.

SPSS tutorials: independent samples t-test (Kent State University)
This tutorial from Kent State University shows how to produce and interpret an independent samples t-test using SPSS.

SPSS tutorials: one-way ANOVA (Kent State University)
This tutorial from Kent State University shows how to produce and interpret a one-way ANOVA. It does not discuss eta.

Confidence intervals (Khan Academy)
This unit from the Khan Academy explains confidence intervals and the relationship between a population mean and a sample mean.

Analysis of variance (Khan Academy)
This unit from the Khan Academy walks through the various statistics (total sum of squares, F-statistic) that are included in an ANOVA test.